LT

Test: Algebraic identities and factorisation

Dynamic tasks on square identities, difference of squares, common factors and polynomial factorisation.

Question qty: 10
Duration in minutes: 21
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Time left: 00:00:00

Sample questions

  • Expand: (x + a)2.
  • Factor out the common factor: ax + a·b.
  • Factorise: x2 − a2.
  • Expand: (x − a)2.
  • A student wrote: (x + a)2 = x2 + a2. What is the error?
  • Which identity correctly represents the difference of two squares?
  • Factorise: x2 + sx + p.
  • In (x + a)2 = x2 + kx + c, find coefficient k.

Algebraic identities and factorisation

The identities (a + b)² = a² + 2ab + b², (a − b)² = a² − 2ab + b² and a² − b² = (a − b)(a + b) help expand and factor expressions efficiently. The middle term of a squared binomial is always twice the product.

Factorisation strategy

First take out any common factor. Then look for a difference of squares or a perfect-square trinomial. Check the result by multiplying the factors back out; sign errors usually appear in the middle term.