Question

(x+6y)^2
u distribute the ^2 right? x^2+36y^2
?

Answer 1

what??

Answer 2

no, there is a formula for this. it looks like this:
(a+b)\[(a+b)^{2}=a ^{2}+2ab+b ^{2}\]

Answer 3

in your example, applying this formula, you have:
\[x ^{2}+12xy+36y ^{2}\]