Question

factorise the following a) a cube-8b cube-24ab-64

Answer 1

take - as common
$- (8b {}^{3} + 24ab + 64)$
$- ((2b) {}^{3} + 3(2b)(4) + 4 {}^{3} )$
$(a + b) {}^{3} = a {}^{3} + b {}^{3} + 3ab$
here a is 2a
b is 4
3ab is 24ab
so
-(2a+4)^3
-(2a+4)(2a+4)(2a+4)
hope it hepled you