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

1 Answer
Mar 25, 2018

(x+2y)3=x3+6x2y+12xy2+8y3

Explanation:

First write it out as (x+2y)(x+2y)(x+2y)
Expand two brackets first, giving: (x2+2xy+2xy+4y2)(x+2y)(x2+4xy+4y2)(x+2y)

Then expand again giving:
x3+2x2y+4x2y+8xy2+4xy2+8y3

Which simplfies to our answer:
x3+6x2y+12xy2+8y3