Question

(a + b)(a ² - ab + b ²) Please help!

Answer 1

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 

Answer 2

Hey there :)

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

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

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

a³ + b³

You can see in the picture I have attached that this is the 7th formula