Question

factorise x raise to the power 6 -7x raise to the power 3 -8

Answer 1

x^6 - 7x^3 -8 =0
(x^3)^2 - 7x^3 -8=0
let x^3 =y

y^2 - 7y -8 =0
y^2 -8y+y-8=0
y(y-8)+1(y-8) =0
(y-8) (y+1) =0
(y-8)=0 or (y+1)=0
y=8 or y= -1
resubstituting y=x^3
x^3=8 or x^3=-1
x=2 or x=-1