Question

Factorize $16x^5-144x^3$ and find its value for x=2. [3 MARKS]

Answer 1

Factorisation: 2 Marks
Substitution: 1 Mark

$16x^5-144x^3$

$=16x^3(x^2-9)$

$=16x^3(x+3)(x-3)$

$x=2$

$=16\left(2{)}^3\right(2+3\left)\right(2-3)$

$=-640$