Question

(x+2y)to the third power equals what?

Answer 1

`(x+2y)^3 = x^3 + 6 x^2 y + 12 x y^2 + 8 y^3`

Explanation:

First write it out as `(x+2y)(x+2y)(x+2y)`
Expand two brackets first, giving: #(x^2+2xy+2xy+4y^2)(x+2y) => (x^2+4xy+4y^2)(x+2y)#

Then expand again giving:
`x^3 + 2x^2y+4x^2y+8xy^2+4xy^2+8y^3`

Which simplfies to our answer:
`x^3 + 6 x^2 y + 12 x y^2 + 8 y^3`