Question

Question 2(iv)
Factorise the following expressions
$-16z+20z^3$

Answer 1

$16z=2\times 2\times 2\times 2\times z20z^3=2\times 2\times 5\times z\times z\times zThecommonfactorsare2,2andz.\therefore -16z+20z^3=-(2\times 2\times 2\times 2\times z)+(2\times 2\times 5\times z\times z\times z)=(2\times 2\times z)[-(2\times 2)+(5\times z\times z\left)\right]=4z(-4+5z^2)$