Class 8 · Chapter 14

Factorisation

Factorising algebraic expressions using common factors, grouping and identities.

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Tip: open the NCERT PDF for the original chapter text alongside the notes here.

Detailed theory

Pull out the greatest common factor from all terms.

6x^2 + 9x = 3x(2x + 3)

Key concepts & formulas

Common factor: pull out the greatest common monomial.

Grouping: pair terms with common factors.

Use identities

a^2-b^2, a^2\pm 2ab+b^2

Trinomial

x^2 + (a+b)x + ab = (x+a)(x+b)

Always take out the GCD first.