Question

if a+ b are the zeroes of x2-2x-8, evaluate a3 + b3

Answer 1

Hello my dear friend this is ur answer:-____________________________________

First factorize x2-2x-8
x^2-2x-8=0
x^2-4x+2x-8=0
x(x-4)+2(x-4)=0

Take common x-4

(x-4)=0 (x+2)=0

x=4 x=-2

Two zeros are 4,-2

Therefore a=4, b=-2

a+b=2

a^3+b^3=a+b(a^2 -ab +b^3)
=2(16-(-8)+(-8))
=2(16+8-8)
=2(16)
=32

This is ur answer i hope this helps u