Question

Factorise: $81-64x^2$

Answer 1

We need to factorise $81-64x^2$y

By using identity $a^2-b^2=(a-b)(a+b)$ we can solve further.

It can be written as

$81-64x^2=\left[\right(9{)}^2-\left(8x{)}^2\right]$

$=(9+8x)(9-8x)$
Thus factors are$(9+8x),(9-8x)$.