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Detailed notes on Algebra for Cambridge IGCSE Mathematics, covering key concepts, explanations, examples, and exam-focused revision points.
Combine like terms, expand brackets, and tidy expressions to their simplest form. The fluency you build here unlocks every other algebraic topic on the paper.
Mapped to the Cambridge IGCSE 0580 syllabus (2025-2027).
Same letters, same powers → like terms. Add their coefficients.
Like terms have identical letter parts (including powers). The coefficient (the number in front) can be different.
| Like? | Why |
|---|---|
| 3x and −7x | Both have x to the power 1. |
| 4x2 and 21x2 | Both have x2. |
| 5xy and −2xy | Both have xy. |
| 3x and 3x2 | NOT like — different powers. |
| 4xy and 4yz | NOT like — different letters. |
Combine like terms by adding the coefficients: 3x+5x−2x=6x. 4x2+7x−3x2+2=(4−3)x2+7x+2=x2+7x+2.
Mixed-letter terms. xy and yx are the SAME thing — order doesn't matter for multiplication. So 5xy+3yx=8xy.
Distribute the multiplier across each term inside the brackets.
Distribution rule: a(b+c)=ab+ac.
The multiplier outside hits EVERY term inside the brackets, signs and all.
Worked. Expand 3(2x+5).
Worked. Expand −2(3x−4).
Worked. Expand and simplify 4(x−2)−3(2x+1).
First, Outside, Inside, Last. Four products to write down before simplifying.
(a+b)(c+d)=ac+ad+bc+bd.
The mnemonic FOIL covers it: First × First, Outside × Outside, Inside × Inside, Last × Last.
Worked. Expand (x+3)(x+5).
Worked. Expand (2x−3)(x+4).
Squaring a binomial. (a+b)2 is NOT a2+b2. It's (a+b)(a+b), expanded: (a+b)2=a2+2ab+b2. (a−b)2=a2−2ab+b2.
Worked. Expand (x−4)2.
Cancel common factors from numerator and denominator. Don't cancel addition unless you can factorise first.
Single-term fractions. Cancel numbers and letters separately. 4x6x3=46×xx3=23x2.
Multi-term: factorise first. Cancellation only works on COMMON FACTORS, not common terms inside an addition. xx2+3x=xx(x+3)=x+3(factorise out x). xx+3=1+3(cannot cancel additive terms).
Worked. Simplify x+2x2−4.
Verbatim phrases and definitions Cambridge mark schemes credit.
Simplifying expressions appears on every paper. Paper 2 has 1-2 mark questions: 'simplify 3x+5y−x+2y', 'expand (x+4)(x−2)'. Paper 4 embeds it inside larger algebra problems. Examiner reports flag (x+3)2=x2+9 and dropping the cross-term as recurring slips.
Sources: Cambridge IGCSE Mathematics 0580 syllabus 2025-2027 (E2.1-2.3); 0580/22 May/Jun 2024 — Q5 (expand and simplify); 0580/42 Oct/Nov 2024 — Q3 (binomial expansion); 0580 Examiner Reports 2022-2024. Last reviewed 2026-05-05.
Step-by-step solutions to past-paper-style questions on simplifying algebraic expressions, written exactly the way a tutor would explain them at the board.
Almost every simplifying algebraic expressions exam question is one of these shapes. Learn to spot each one and you will always know how to start.
Recognise it by
A single instruction — simplify, expand, expand and simplify — on one expression. One method, one tidied answer.
How to approach it
Decide whether the task is collecting like terms, expanding brackets, or applying index laws — then show each line: distribute or FOIL first, collect like terms last. Write all sub-products on separate lines before combining.
Common trap
Sign slips when a bracket follows a minus sign — −2(x−3) becomes −2x+6, not −2x−6. Examiner reports also flag (2x2)3 written as 2x6 instead of 8x6: the power hits the coefficient too.
Recognise it by
Several brackets chained together — for example a product of three brackets — so one expansion feeds into the next.
How to approach it
Expand two brackets fully first, simplify that result, then multiply the trinomial by the remaining bracket term by term. Lay out every product before collecting like terms.
Common trap
Dropping a single term during the second expansion. Examiner reports note candidates rush the multi-bracket stage — write all products in full, then collect.
Question
Simplify 4x+3y−2x+5y−7.
Step-by-step solution
Step 1
Group like terms together.
(4x−2x)+(3y+5y)−7
Step 2
Combine each group.
=2x+8y−7
Answer
2x+8y−7
Examiner tip
Treat each variable as its own currency: x-terms only combine with x-terms; y-terms with y-terms; numbers with numbers.
Question
Expand 3(2x−5).
Step-by-step solution
Step 1
Multiply each term inside the bracket by 3.
3×2x−3×5
Step 2
Simplify.
=6x−15
Answer
6x−15
Question
Expand and simplify (2x−3)(x+4).
Step-by-step solution
Step 1
Use FOIL — First, Outer, Inner, Last.
(2x)(x)+(2x)(4)+(−3)(x)+(−3)(4)
Step 2
Compute each product.
=2x2+8x−3x−12
Step 3
Collect the x terms.
=2x2+5x−12
Answer
2x2+5x−12
Examiner tip
Watch the sign on the −3. Many students drop it and write +3x instead of −3x, losing the accuracy mark.
Question
Simplify 4a2b12a5b3.
Step-by-step solution
Step 1
Divide the coefficients.
412=3
Step 2
Subtract powers for the variables.
a5−2=a3,b3−1=b2
Step 3
Combine.
=3a3b2
Answer
3a3b2
Question
Simplify 5x−2(x−3)+4.
Step-by-step solution
Step 1
Distribute the −2 across the bracket.
5x−2x+6+4
Step 2
Collect like terms.
=3x+10
Answer
3x+10
Examiner tip
−2(x−3) becomes −2x+6, not −2x−6. The minus sign flips the sign of every term inside.
Question
Simplify 4a2b−3ab2+5a2b+2ab2−a2b.
Step-by-step solution
Step 1
Identify like terms. a2b and ab2 are NOT alike — the powers on each variable differ.
Step 2
Group the a2b terms.
(4a2b+5a2b−a2b)=8a2b
Step 3
Group the ab2 terms.
(−3ab2+2ab2)=−ab2
Step 4
Combine.
=8a2b−ab2
Answer
8a2b−ab2
Examiner tip
The examiner report flags candidates often merge a2b with ab2 — they are unlike because the exponents on each variable differ. Match every power before combining.
Question
Simplify 36x+9−24x−8.
Step-by-step solution
Step 1
Divide each term in the first numerator by 3.
36x+9=2x+3
Step 2
Divide each term in the second numerator by 2.
24x−8=2x−4
Step 3
Subtract, distributing the minus sign.
(2x+3)−(2x−4)=2x+3−2x+4
Step 4
Collect like terms.
=7
Answer
7
Examiner tip
The 2024 mark scheme awards method marks for distributing the denominator across BOTH terms in the numerator. Dividing only one term is the dominant error.
Question
Simplify 4x5(2x2)3×5x4.
Step-by-step solution
Step 1
Apply the power to each factor inside the bracket.
(2x2)3=23×x6=8x6
Step 2
Multiply the numerator.
8x6×5x4=40x10
Step 3
Divide by the denominator.
4x540x10=10x5
Answer
10x5
Examiner tip
Examiners often see (2x2)3 written as 2x6 instead of 8x6. The power applies to every factor inside the bracket, including the coefficient.
Question
Expand and simplify (3x−4)2.
Step-by-step solution
Step 1
Write the squared bracket as a product of two identical brackets.
(3x−4)2=(3x−4)(3x−4)
Step 2
Use FOIL.
=9x2−12x−12x+16
Step 3
Collect the middle terms.
=9x2−24x+16
Answer
9x2−24x+16
Examiner tip
The examiner report flags candidates often write (3x−4)2=9x2+16 — dropping the cross-term. (a−b)2=a2−2ab+b2; the middle term −2ab is never zero.
Question
Expand and simplify (x+1)(x−2)(x+3).
Step-by-step solution
Step 1
Expand the first two brackets using FOIL.
(x+1)(x−2)=x2−2x+x−2=x2−x−2
Step 2
Multiply that trinomial by (x+3) term by term.
(x2−x−2)(x+3)
Step 3
Distribute each term of the trinomial.
=x2(x+3)−x(x+3)−2(x+3)=x3+3x2−x2−3x−2x−6
Step 4
Collect like terms.
=x3+2x2−5x−6
Answer
x3+2x2−5x−6
Examiner tip
The examiner report flags candidates often lose marks by dropping a single term during the second expansion. Write all six products on separate lines before collecting like terms — it costs time but secures every mark.
The formulae you need to memorise for simplifying algebraic expressions on the Cambridge IGCSE 0580 paper, with every variable defined in plain English and a note on when to use it.
a(b+c)=ab+ac
When to use
Whenever you need to remove brackets in a single-bracket expansion.
(a+b)(c+d)=ac+ad+bc+bd
When to use
Use FOIL (First, Outer, Inner, Last) for (linear)(linear) expansions.
am⋅an=am+n, anam=am−n, (am)n=amn
When to use
Whenever you simplify expressions with variables raised to powers.
Definitions to memorise and the exact keywords mark schemes credit for simplifying algebraic expressions answers — sharpened from recent examiner reports for the 2026 0580 sitting.
Terms with the same variables raised to the same powers. Their coefficients can be added or subtracted.
Example
3x2 and −7x2 are like terms; 3x2 and 3x are not.
Multiply out brackets so the expression has no brackets remaining.
Rewrite the expression in its shortest equivalent form by collecting like terms or applying index laws.
The numerical multiplier of a variable.
Example
In −4xy, the coefficient is −4.
A monomial has one term (3x2), a binomial two (3x+5), a trinomial three (x2+2x+1).
The traps other students keep falling into on simplifying algebraic expressions questions — taken from recent Cambridge IGCSE 0580 examiner reports and mark schemes — and how to avoid them.
0580/22 — recurring across recent series
Why it happens
Students focus on the first FOIL product and forget to carry the negative through.
How to avoid it
Write each of the four products on a separate line before collecting like terms.
Why it happens
−2(x−3) gets written as −2x−6 instead of −2x+6.
How to avoid it
Treat the minus as −1×…. The sign flips on every term inside.
Why it happens
(2x)3 is written as 2x3 instead of 8x3.
How to avoid it
(2x)3=23⋅x3=8x3. Apply the power to every factor inside the bracket.
Why it happens
a3⋅a2 becomes a6 (incorrect) instead of a5.
How to avoid it
Multiplying same-base terms → ADD indices. Raising a power to a power → MULTIPLY indices.
Why it happens
3x+4y gets simplified to 7xy — but x and y are different variables.
How to avoid it
Only combine terms with identical variables AND identical powers.
The things students keep getting wrong in this sub-topic, answered.