Question

(a - b)(a 2 + ab + b 2) HELP

Answer 1

Hey there :)

( a - b )( a² + ab + b² )
Let us distribute ( a - b ) into the other

a ( a² ) + a ( ab ) + a ( b² ) - b ( a² ) - b ( ab ) - b ( b² )
a³ + a²b + ab² - a²b - ab² - b³

We can further simplify
a²b - ab² = 0
ab² - ab² = 0

a³ - b³

You can see in the picture which I have attached. It is the 8th formula

Answer 2

Use FOIL. 

(a - b)(a^2 + ab + b^2) 
a^3 + a^2b + b^2a - a^2b - b^2a - b^3
a^3 - b^3 <----------Answer