O Level MathematicsC2.2 Algebraic manipulation (simplify, expand, factorise common factor and products of two brackets).

πŸ”’ Mastering Algebraic Manipulation Made Easy!

Edudent Academy
11 Dec 25

Algebra is a universal language of patterns and relationships. Being able to **simplify, expand, and factorise** expressions quickly is essential for acing O-Level examsβ€”these skills cut through messy questions and reveal the answers faster.

Main Concept: Simplify, Expand, Factorise

We usually start by simplifying terms (collecting like terms), then **expanding** products such as (a+b)(c+d)(a+b)(c+d), and finally **factorising**β€”the reverse processβ€”by taking out common factors or reversing double brackets. Mastery of these moves turns long algebra questions into one-liners!

  • Combine like terms: 3x+7x=10x3x + 7x = 10x
  • Expand brackets: (2xβˆ’5)(x+4)=2x2+3xβˆ’20(2x-5)(x+4) = 2x^2 + 3x - 20
  • Factorise common factor: 6xyβˆ’9y=3y(2xβˆ’3)6xy - 9y = 3y(2x - 3)
  • Factorise quadratic form: x2+2xβˆ’35=(x+7)(xβˆ’5)x^2 + 2x - 35 = (x+7)(x-5)

Worked Example: Expand & Factorise in One Go

Problem: Simplify β€…β€Š(2x+3)(xβˆ’4)+5x \;(2x + 3)(x - 4) + 5x\, and then factorise the final answer.

  • Step 1: Expand (2x+3)(xβˆ’4)β€…β€Šβ‡’β€…β€Š2xΓ—x+2xΓ—(βˆ’4)+3Γ—x+3Γ—(βˆ’4)=2x2βˆ’8x+3xβˆ’12(2x + 3)(x - 4) \;\Rightarrow\; 2x \times x + 2x \times (-4) + 3 \times x + 3 \times (-4) = 2x^2 - 8x + 3x - 12
  • Step 2: Combine like terms: 2x2βˆ’5xβˆ’122x^2 - 5x - 12
  • Step 3: Add 5x5x: 2x2βˆ’5xβˆ’12+5x=2x2βˆ’122x^2 - 5x - 12 + 5x = 2x^2 - 12
  • Step 4: Factorise common factor 22: 2x2βˆ’12=2(x2βˆ’6)2x^2 - 12 = 2(x^2 - 6)

Practice makes perfect! Work through past-paper questions, time yourself, and always check by expanding your factorised answers. The more you wrestle with algebra, the faster and more accurate you’ll become.