What are algebraic fractions and how do they differ from numerical fractions?

Algebraic fractions are fractions where the numerator, the denominator, or both contain algebraic expressions, such as variables and constants. Unlike numerical fractions, which only involve numbers, algebraic fractions require understanding of algebraic operations to simplify or solve them. This concept is crucial in the Cambridge IGCSE Mathematics curriculum as it builds foundational skills for more advanced algebra topics.

How do you simplify algebraic fractions?

To simplify algebraic fractions, you need to factor both the numerator and the denominator to their simplest forms and then cancel out any common factors. For example, in the fraction (x^2 - 4)/(x^2 - 2x), factor the numerator as (x + 2)(x - 2) and the denominator as x(x - 2). The common factor (x - 2) can be canceled, simplifying the fraction to (x + 2)/x. This process is a key skill in the Cambridge IGCSE Mathematics syllabus.

How do you add or subtract algebraic fractions?

To add or subtract algebraic fractions, you must first find a common denominator, similar to numerical fractions. Once a common denominator is established, adjust the numerators accordingly and perform the addition or subtraction. For example, to add (1/x) + (2/y), the common denominator is xy, resulting in (y + 2x)/(xy). Mastery of this technique is essential for success in Cambridge IGCSE Algebra.

What is the process for multiplying and dividing algebraic fractions?

Multiplying algebraic fractions involves multiplying the numerators together and the denominators together. For example, (a/b) * (c/d) = (ac)/(bd). For division, multiply by the reciprocal of the divisor: (a/b) ÷ (c/d) = (a/b) * (d/c) = (ad)/(bc). Simplifying the resulting fraction is often necessary. These operations are fundamental in the Cambridge IGCSE Mathematics curriculum, reinforcing algebraic manipulation skills.

How do you solve equations involving algebraic fractions?

To solve equations with algebraic fractions, first eliminate the fractions by multiplying every term by the least common denominator (LCD) of all the fractions involved. This transforms the equation into a polynomial equation, which can be solved using standard algebraic methods. For example, solving (1/x) + (2/y) = 3 involves multiplying through by xy to get y + 2x = 3xy, then solving for the variable. This technique is a critical component of the Cambridge IGCSE Mathematics syllabus.

Why is "Cancelling individual terms instead of factors" a common mistake in Algebraic Fractions?

Why it happens: Students see x + 3/x + 1 and try to cancel the x's, leaving 3/1 = 3. How to avoid it: Cancellation only works for **shared factors** (the whole bracket). Factorise first, then cancel. Source: 0580/42 — examiner reports, recurring

Why is "Adding fractions without a common denominator" a common mistake in Algebraic Fractions?

Why it happens: Adding numerators and denominators directly: 2/x+1 + 3/x-2 ≠ 5/2x - 1. How to avoid it: Always rewrite over a common denominator first.

Why is "Flipping the wrong fraction in a division" a common mistake in Algebraic Fractions?

Why it happens: Students flip the first fraction instead of the second. How to avoid it: Rule: keep the first, change division to multiplication, flip the SECOND.

Why is "Not factorising before simplifying" a common mistake in Algebraic Fractions?

Why it happens: Skipping the factorisation step leaves no shared factors to cancel. How to avoid it: Step 1 is **always** factorise — both numerator and denominator. Then look for shared factors.

AlgebraCambridge IGCSE Mathematics (0580)

Algebraic Fractions

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next.

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Algebraic Fractions — Cambridge IGCSE 0580 Maths Extended (2026)

Same arithmetic as ordinary fractions, just with letters. Add, subtract, multiply, divide and simplify rational expressions confidently — Paper 4 will reward fluency.

What you’ll learn

Mapped to the Cambridge IGCSE 0580 syllabus (2025-2027).

E2.6 — Manipulate algebraic fractions including addition, subtraction, multiplication and division.

Simplifying algebraic fractions

Factorise top and bottom; cancel common FACTORS, never common terms inside an addition.

Procedure.

Factorise the numerator.
Factorise the denominator.
Cancel any factor common to both.

Worked. Simplify $\dfrac{6x^{2}}{9x}$ .

Both: factor numbers and letters separately. $\dfrac{6}{9} = \dfrac{2}{3}$ . $\dfrac{x^{2}}{x} = x$ .
Result: $\dfrac{2x}{3}$ .

Worked. Simplify $\dfrac{x^{2} - 9}{x + 3}$ .

Top is difference of two squares: $(x + 3)(x - 3)$ .
$\dfrac{(x + 3)(x - 3)}{x + 3} = x - 3$ .

Worked. Simplify $\dfrac{x^{2} + 5x + 6}{x + 2}$ .

Factorise top: $(x + 2)(x + 3)$ .
Cancel $(x + 2)$ : $x + 3$ .

Crucial caveat. $\dfrac{x + 3}{x}$ does NOT simplify to $1 + 3 = 4$ . The $x$ on the bottom is not a common FACTOR — only common factors cancel.

Factorise BEFORE cancelling.
Cancel only common FACTORS.
Difference of two squares often appears on top.
Final answers in simplest form.

Adding and subtracting algebraic fractions

Find a common denominator first. Distribute the minus sign carefully when subtracting.

Same denominator → just combine numerators. $\dfrac{2x}{5} + \dfrac{x}{5} = \dfrac{3x}{5}.$

Different denominators → find a common one. The simplest common denominator is usually the PRODUCT, but the LCM is more efficient if there's a shared factor.

Worked. $\dfrac{2}{x} + \dfrac{3}{x + 1}$ .

Common denominator: $x(x + 1)$ .
$\dfrac{2(x + 1)}{x(x + 1)} + \dfrac{3x}{x(x + 1)} = \dfrac{2(x + 1) + 3x}{x(x + 1)} = \dfrac{2x + 2 + 3x}{x(x + 1)} = \dfrac{5x + 2}{x(x + 1)}$ .

Worked (subtraction). $\dfrac{x + 1}{2} - \dfrac{x - 3}{4}$ .

Common denominator: $4$ .
$\dfrac{2(x + 1)}{4} - \dfrac{x - 3}{4} = \dfrac{2(x + 1) - (x - 3)}{4}$ .
Distribute the minus: $\dfrac{2x + 2 - x + 3}{4} = \dfrac{x + 5}{4}$ .

The sign trap. When subtracting, the minus applies to EVERY term in the numerator of the second fraction. Use brackets to keep yourself honest: $- (x - 3)$ becomes $-x + 3$ .

Common denominator first.
Combine numerators after equalising denominators.
Distribute the minus sign across the entire second numerator.
Simplify the final fraction if possible.

Multiplying and dividing algebraic fractions

Multiply: top × top, bottom × bottom, then simplify. Divide: flip the second fraction and multiply.

Multiplication. $\dfrac{a}{b} \times \dfrac{c}{d} = \dfrac{ac}{bd}$ . Cancel BEFORE multiplying.

Worked. $\dfrac{x + 2}{3} \times \dfrac{6}{x^{2} - 4}$ .

Factorise: $x^{2} - 4 = (x + 2)(x - 2)$ .
$\dfrac{(x + 2)}{3} \times \dfrac{6}{(x + 2)(x - 2)}$ .
Cancel $(x + 2)$ : $\dfrac{1}{3} \times \dfrac{6}{x - 2} = \dfrac{6}{3(x - 2)} = \dfrac{2}{x - 2}$ .

Division. $\dfrac{a}{b} \div \dfrac{c}{d} = \dfrac{a}{b} \times \dfrac{d}{c}$ . Flip the second fraction, then multiply.

Worked. $\dfrac{x + 1}{2x} \div \dfrac{(x + 1)^{2}}{4}$ .

Flip: $\dfrac{x + 1}{2x} \times \dfrac{4}{(x + 1)^{2}}$ .
Cancel $(x + 1)$ once: $\dfrac{1}{2x} \times \dfrac{4}{x + 1} = \dfrac{4}{2x(x + 1)} = \dfrac{2}{x(x + 1)}$ .

Multiply: top × top, bottom × bottom.
Divide: multiply by the reciprocal of the second fraction.
Cancel BEFORE multiplying — saves work.
Always factorise both fractions first.

How it’s examined

Algebraic fractions show up most years on Paper 4 as 3-4 mark questions: simplify, then sometimes use the result inside an equation. Paper 2 has the simpler form (single fraction simplification, 1-2 marks). Examiner reports flag the sign mistake when subtracting (forgetting to distribute the minus) and cancelling individual additive terms.

Sources: Cambridge IGCSE Mathematics 0580 syllabus 2025-2027 (E2.6); 0580/22 May/Jun 2024 — Q14 (simplify fraction); 0580/42 Oct/Nov 2024 — Q11 (combine fractions); 0580 Examiner Reports 2022-2024. Last reviewed 2026-05-05.

Master this Topic

Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

Take this whole topic with you

Download a branded revision sheet — worked examples, formulae, definitions and common mistakes for Algebraic Fractions, ready to print or save as PDF.

Step-by-step worked examples — Algebraic Fractions

Step-by-step solutions to past-paper-style questions on algebraic fractions, written exactly the way a tutor would explain them at the board.

1Simplify by factorising and cancelling
Extended• simplifying
Question
Simplify $\dfrac{x^{2} - 9}{x^{2} - 4x + 3}$ .
Step-by-step solution
1. Step 1
  Factorise numerator (difference of two squares).
  $x^{2} - 9 = (x + 3)(x - 3)$
2. Step 2
  Factorise denominator.
  $x^{2} - 4x + 3 = (x - 1)(x - 3)$
3. Step 3
  Cancel the common factor $(x-3)$ .
  $\dfrac{(x+3)(x-3)}{(x-1)(x-3)} = \dfrac{x+3}{x-1}$
Answer
$\dfrac{x+3}{x-1}$
Examiner tip
You can only cancel factors, never individual terms. $\dfrac{x+3}{x+1}$ does NOT simplify to $\dfrac{3}{1} = 3$ .
2Add two algebraic fractions
Extended• Adapted from 0580/42 May/Jun 2024 Q14• addition
Question
Express $\dfrac{2}{x + 1} + \dfrac{3}{x - 2}$ as a single fraction in simplest form.
Step-by-step solution
1. Step 1
  Common denominator is $(x+1)(x-2)$ .
  $\dfrac{2(x-2)}{(x+1)(x-2)} + \dfrac{3(x+1)}{(x+1)(x-2)}$
2. Step 2
  Combine numerators.
  $\dfrac{2(x-2) + 3(x+1)}{(x+1)(x-2)}$
3. Step 3
  Expand and simplify the numerator.
  $\dfrac{2x - 4 + 3x + 3}{(x+1)(x-2)} = \dfrac{5x - 1}{(x+1)(x-2)}$
Answer
$\dfrac{5x - 1}{(x + 1)(x - 2)}$
3Multiply algebraic fractions
Extended• multiplication
Question
Simplify $\dfrac{x^{2} - 1}{x + 2} \times \dfrac{x + 2}{x - 1}$ .
Step-by-step solution
1. Step 1
  Factorise the difference of two squares.
  $\dfrac{(x+1)(x-1)}{x+2} \times \dfrac{x+2}{x-1}$
2. Step 2
  Cancel $(x+2)$ and $(x-1)$ .
  $= x + 1$
Answer
$x + 1$
4Divide algebraic fractions
Extended• division
Question
Simplify $\dfrac{2x + 6}{x^{2}} \div \dfrac{x + 3}{4x}$ .
Step-by-step solution
1. Step 1
  Flip the second fraction and multiply.
  $\dfrac{2x + 6}{x^{2}} \times \dfrac{4x}{x + 3}$
2. Step 2
  Factorise $2x + 6 = 2(x + 3)$ .
  $\dfrac{2(x+3)}{x^{2}} \times \dfrac{4x}{x+3}$
3. Step 3
  Cancel $(x+3)$ and one $x$ .
  $= \dfrac{2 \cdot 4}{x} = \dfrac{8}{x}$
Answer
$\dfrac{8}{x}$

Key Formulae — Algebraic Fractions

The formulae you need to memorise for algebraic fractions on the Cambridge IGCSE 0580 paper, with every variable defined in plain English and a note on when to use it.

Cancellation rule
$\dfrac{ac}{bc} = \dfrac{a}{b},\quad c \neq 0$
When to use
Only when the same FACTOR appears in numerator and denominator — never with individual terms.
Adding fractions over a common denominator
$\dfrac{a}{b} + \dfrac{c}{d} = \dfrac{ad + bc}{bd}$
When to use
Adding or subtracting any two fractions with different denominators.
Dividing fractions
$\dfrac{a}{b} \div \dfrac{c}{d} = \dfrac{a}{b} \times \dfrac{d}{c}$
When to use
Always rewrite a division as multiplication by the reciprocal.

Key Definitions and Keywords — Algebraic Fractions

Definitions to memorise and the exact keywords mark schemes credit for algebraic fractions answers — sharpened from recent examiner reports for the 2026 0580 sitting.

Algebraic fraction
Examiner keyword
A fraction whose numerator and/or denominator contain algebraic expressions (variables).
Example
$\dfrac{x + 1}{x - 2}$
Common denominator
Examiner keyword
A denominator shared by two or more fractions, used to combine them by addition or subtraction.
Reciprocal of a fraction
The reciprocal of $\dfrac{a}{b}$ is $\dfrac{b}{a}$ .
Excluded values
Values of the variable that make any denominator zero — these are excluded from the domain because division by zero is undefined.
Example
In $\dfrac{1}{x - 2}$ , $x = 2$ is excluded.

Common Mistakes and Misconceptions — Algebraic Fractions

The traps other students keep falling into on algebraic fractions questions — taken from recent Cambridge IGCSE 0580 examiner reports and mark schemes — and how to avoid them.

✕Cancelling individual terms instead of factors
0580/42 — examiner reports, recurring
Why it happens
Students see $\dfrac{x + 3}{x + 1}$ and try to cancel the $x$ 's, leaving $\dfrac{3}{1} = 3$ .
How to avoid it
Cancellation only works for shared factors (the whole bracket). Factorise first, then cancel.
✕Adding fractions without a common denominator
Why it happens
Adding numerators and denominators directly: $\dfrac{2}{x+1} + \dfrac{3}{x-2} \neq \dfrac{5}{2x - 1}$ .
How to avoid it
Always rewrite over a common denominator first.
✕Flipping the wrong fraction in a division
Why it happens
Students flip the first fraction instead of the second.
How to avoid it
Rule: keep the first, change division to multiplication, flip the SECOND.
✕Not factorising before simplifying
Why it happens
Skipping the factorisation step leaves no shared factors to cancel.
How to avoid it
Step 1 is always factorise — both numerator and denominator. Then look for shared factors.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Video lesson

Short walkthrough of the concepts students most often get stuck on.

Algebraic Fractions — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

AlgebraCambridge IGCSE Mathematics (0580)

Algebraic Fractions

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next.

Previous Next

Learn this Topic

Start with the slides for the quick version, then go deeper with the full study notes.

Short Study Notes in the form of Slides

Read the notes first. If the method in a worked example clicks, you're ready for the questions.

Page 1 / 0

Detailed Study Notes

Full prose, callouts and a recap — built for A* mastery, not just a quick scan.

Take these study notes with you

Download a branded PDF — full prose, callouts, recap and memorise list for Algebraic Fractions, ready to print or save offline.

Algebraic Fractions — Cambridge IGCSE 0580 Maths Extended (2026)

Same arithmetic as ordinary fractions, just with letters. Add, subtract, multiply, divide and simplify rational expressions confidently — Paper 4 will reward fluency.

What you’ll learn

Mapped to the Cambridge IGCSE 0580 syllabus (2025-2027).

E2.6 — Manipulate algebraic fractions including addition, subtraction, multiplication and division.

Simplifying algebraic fractions

Factorise top and bottom; cancel common FACTORS, never common terms inside an addition.

Procedure.

Factorise the numerator.
Factorise the denominator.
Cancel any factor common to both.

Worked. Simplify $\dfrac{6x^{2}}{9x}$ .

Both: factor numbers and letters separately. $\dfrac{6}{9} = \dfrac{2}{3}$ . $\dfrac{x^{2}}{x} = x$ .
Result: $\dfrac{2x}{3}$ .

Worked. Simplify $\dfrac{x^{2} - 9}{x + 3}$ .

Top is difference of two squares: $(x + 3)(x - 3)$ .
$\dfrac{(x + 3)(x - 3)}{x + 3} = x - 3$ .

Worked. Simplify $\dfrac{x^{2} + 5x + 6}{x + 2}$ .

Factorise top: $(x + 2)(x + 3)$ .
Cancel $(x + 2)$ : $x + 3$ .

Crucial caveat. $\dfrac{x + 3}{x}$ does NOT simplify to $1 + 3 = 4$ . The $x$ on the bottom is not a common FACTOR — only common factors cancel.

Factorise BEFORE cancelling.
Cancel only common FACTORS.
Difference of two squares often appears on top.
Final answers in simplest form.

Adding and subtracting algebraic fractions

Find a common denominator first. Distribute the minus sign carefully when subtracting.

Same denominator → just combine numerators. $\dfrac{2x}{5} + \dfrac{x}{5} = \dfrac{3x}{5}.$

Different denominators → find a common one. The simplest common denominator is usually the PRODUCT, but the LCM is more efficient if there's a shared factor.

Worked. $\dfrac{2}{x} + \dfrac{3}{x + 1}$ .

Common denominator: $x(x + 1)$ .
$\dfrac{2(x + 1)}{x(x + 1)} + \dfrac{3x}{x(x + 1)} = \dfrac{2(x + 1) + 3x}{x(x + 1)} = \dfrac{2x + 2 + 3x}{x(x + 1)} = \dfrac{5x + 2}{x(x + 1)}$ .

Worked (subtraction). $\dfrac{x + 1}{2} - \dfrac{x - 3}{4}$ .

Common denominator: $4$ .
$\dfrac{2(x + 1)}{4} - \dfrac{x - 3}{4} = \dfrac{2(x + 1) - (x - 3)}{4}$ .
Distribute the minus: $\dfrac{2x + 2 - x + 3}{4} = \dfrac{x + 5}{4}$ .

The sign trap. When subtracting, the minus applies to EVERY term in the numerator of the second fraction. Use brackets to keep yourself honest: $- (x - 3)$ becomes $-x + 3$ .

Common denominator first.
Combine numerators after equalising denominators.
Distribute the minus sign across the entire second numerator.
Simplify the final fraction if possible.

Multiplying and dividing algebraic fractions

Multiply: top × top, bottom × bottom, then simplify. Divide: flip the second fraction and multiply.

Multiplication. $\dfrac{a}{b} \times \dfrac{c}{d} = \dfrac{ac}{bd}$ . Cancel BEFORE multiplying.

Worked. $\dfrac{x + 2}{3} \times \dfrac{6}{x^{2} - 4}$ .

Factorise: $x^{2} - 4 = (x + 2)(x - 2)$ .
$\dfrac{(x + 2)}{3} \times \dfrac{6}{(x + 2)(x - 2)}$ .
Cancel $(x + 2)$ : $\dfrac{1}{3} \times \dfrac{6}{x - 2} = \dfrac{6}{3(x - 2)} = \dfrac{2}{x - 2}$ .

Division. $\dfrac{a}{b} \div \dfrac{c}{d} = \dfrac{a}{b} \times \dfrac{d}{c}$ . Flip the second fraction, then multiply.

Worked. $\dfrac{x + 1}{2x} \div \dfrac{(x + 1)^{2}}{4}$ .

Flip: $\dfrac{x + 1}{2x} \times \dfrac{4}{(x + 1)^{2}}$ .
Cancel $(x + 1)$ once: $\dfrac{1}{2x} \times \dfrac{4}{x + 1} = \dfrac{4}{2x(x + 1)} = \dfrac{2}{x(x + 1)}$ .

Multiply: top × top, bottom × bottom.
Divide: multiply by the reciprocal of the second fraction.
Cancel BEFORE multiplying — saves work.
Always factorise both fractions first.

How it’s examined

Master this Topic

Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

Take this whole topic with you

Download a branded revision sheet — worked examples, formulae, definitions and common mistakes for Algebraic Fractions, ready to print or save as PDF.

Step-by-step worked examples — Algebraic Fractions

Step-by-step solutions to past-paper-style questions on algebraic fractions, written exactly the way a tutor would explain them at the board.

1Simplify by factorising and cancelling
Extended• simplifying
Question
Simplify $\dfrac{x^{2} - 9}{x^{2} - 4x + 3}$ .
Step-by-step solution
1. Step 1
  Factorise numerator (difference of two squares).
  $x^{2} - 9 = (x + 3)(x - 3)$
2. Step 2
  Factorise denominator.
  $x^{2} - 4x + 3 = (x - 1)(x - 3)$
3. Step 3
  Cancel the common factor $(x-3)$ .
  $\dfrac{(x+3)(x-3)}{(x-1)(x-3)} = \dfrac{x+3}{x-1}$
Answer
$\dfrac{x+3}{x-1}$
Examiner tip
You can only cancel factors, never individual terms. $\dfrac{x+3}{x+1}$ does NOT simplify to $\dfrac{3}{1} = 3$ .
2Add two algebraic fractions
Extended• Adapted from 0580/42 May/Jun 2024 Q14• addition
Question
Express $\dfrac{2}{x + 1} + \dfrac{3}{x - 2}$ as a single fraction in simplest form.
Step-by-step solution
1. Step 1
  Common denominator is $(x+1)(x-2)$ .
  $\dfrac{2(x-2)}{(x+1)(x-2)} + \dfrac{3(x+1)}{(x+1)(x-2)}$
2. Step 2
  Combine numerators.
  $\dfrac{2(x-2) + 3(x+1)}{(x+1)(x-2)}$
3. Step 3
  Expand and simplify the numerator.
  $\dfrac{2x - 4 + 3x + 3}{(x+1)(x-2)} = \dfrac{5x - 1}{(x+1)(x-2)}$
Answer
$\dfrac{5x - 1}{(x + 1)(x - 2)}$
3Multiply algebraic fractions
Extended• multiplication
Question
Simplify $\dfrac{x^{2} - 1}{x + 2} \times \dfrac{x + 2}{x - 1}$ .
Step-by-step solution
1. Step 1
  Factorise the difference of two squares.
  $\dfrac{(x+1)(x-1)}{x+2} \times \dfrac{x+2}{x-1}$
2. Step 2
  Cancel $(x+2)$ and $(x-1)$ .
  $= x + 1$
Answer
$x + 1$
4Divide algebraic fractions
Extended• division
Question
Simplify $\dfrac{2x + 6}{x^{2}} \div \dfrac{x + 3}{4x}$ .
Step-by-step solution
1. Step 1
  Flip the second fraction and multiply.
  $\dfrac{2x + 6}{x^{2}} \times \dfrac{4x}{x + 3}$
2. Step 2
  Factorise $2x + 6 = 2(x + 3)$ .
  $\dfrac{2(x+3)}{x^{2}} \times \dfrac{4x}{x+3}$
3. Step 3
  Cancel $(x+3)$ and one $x$ .
  $= \dfrac{2 \cdot 4}{x} = \dfrac{8}{x}$
Answer
$\dfrac{8}{x}$

Key Formulae — Algebraic Fractions

The formulae you need to memorise for algebraic fractions on the Cambridge IGCSE 0580 paper, with every variable defined in plain English and a note on when to use it.

Cancellation rule
$\dfrac{ac}{bc} = \dfrac{a}{b},\quad c \neq 0$
When to use
Only when the same FACTOR appears in numerator and denominator — never with individual terms.
Adding fractions over a common denominator
$\dfrac{a}{b} + \dfrac{c}{d} = \dfrac{ad + bc}{bd}$
When to use
Adding or subtracting any two fractions with different denominators.
Dividing fractions
$\dfrac{a}{b} \div \dfrac{c}{d} = \dfrac{a}{b} \times \dfrac{d}{c}$
When to use
Always rewrite a division as multiplication by the reciprocal.

Key Definitions and Keywords — Algebraic Fractions

Definitions to memorise and the exact keywords mark schemes credit for algebraic fractions answers — sharpened from recent examiner reports for the 2026 0580 sitting.

Algebraic fraction
Examiner keyword
A fraction whose numerator and/or denominator contain algebraic expressions (variables).
Example
$\dfrac{x + 1}{x - 2}$
Common denominator
Examiner keyword
A denominator shared by two or more fractions, used to combine them by addition or subtraction.
Reciprocal of a fraction
The reciprocal of $\dfrac{a}{b}$ is $\dfrac{b}{a}$ .
Excluded values
Values of the variable that make any denominator zero — these are excluded from the domain because division by zero is undefined.
Example
In $\dfrac{1}{x - 2}$ , $x = 2$ is excluded.

Common Mistakes and Misconceptions — Algebraic Fractions

The traps other students keep falling into on algebraic fractions questions — taken from recent Cambridge IGCSE 0580 examiner reports and mark schemes — and how to avoid them.

✕Cancelling individual terms instead of factors
0580/42 — examiner reports, recurring
Why it happens
Students see $\dfrac{x + 3}{x + 1}$ and try to cancel the $x$ 's, leaving $\dfrac{3}{1} = 3$ .
How to avoid it
Cancellation only works for shared factors (the whole bracket). Factorise first, then cancel.
✕Adding fractions without a common denominator
Why it happens
Adding numerators and denominators directly: $\dfrac{2}{x+1} + \dfrac{3}{x-2} \neq \dfrac{5}{2x - 1}$ .
How to avoid it
Always rewrite over a common denominator first.
✕Flipping the wrong fraction in a division
Why it happens
Students flip the first fraction instead of the second.
How to avoid it
Rule: keep the first, change division to multiplication, flip the SECOND.
✕Not factorising before simplifying
Why it happens
Skipping the factorisation step leaves no shared factors to cancel.
How to avoid it
Step 1 is always factorise — both numerator and denominator. Then look for shared factors.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Video lesson

Short walkthrough of the concepts students most often get stuck on.

Algebraic Fractions — frequently asked questions

The things students keep getting wrong in this sub-topic, answered.

Algebraic Fractions

Short Study Notes in the form of Slides

Detailed Study Notes

What you’ll learn

How it’s examined

1Simplify by factorising and cancelling

2Add two algebraic fractions

3Multiply algebraic fractions

4Divide algebraic fractions

Cancellation rule

Adding fractions over a common denominator

Dividing fractions

Algebraic fraction

Common denominator

Reciprocal of a fraction

Excluded values

✕Cancelling individual terms instead of factors

✕Adding fractions without a common denominator

✕Flipping the wrong fraction in a division

✕Not factorising before simplifying

Practice questions

Past paper style quiz

Assess your understanding

Video lesson

Algebraic Fractions — frequently asked questions

Algebraic Fractions

Short Study Notes in the form of Slides

Detailed Study Notes

What you’ll learn

How it’s examined

1Simplify by factorising and cancelling

2Add two algebraic fractions

3Multiply algebraic fractions

4Divide algebraic fractions

Cancellation rule

Adding fractions over a common denominator

Dividing fractions

Algebraic fraction

Common denominator

Reciprocal of a fraction

Excluded values

✕Cancelling individual terms instead of factors

✕Adding fractions without a common denominator

✕Flipping the wrong fraction in a division

✕Not factorising before simplifying

Practice questions

Past paper style quiz

Assess your understanding

Video lesson

Algebraic Fractions — frequently asked questions