# How do you factor #x^2+6xy+9y^2# ?

##### 1 Answer

Oct 7, 2016

#### Explanation:

Notice that both

So we can try squaring

#(x+3y)^2 = (x+3y)(x+3y) = x^2+6xy+9y^2#

So

In general we have:

#(a+b)^2 = a^2+2ab+b^2#

So we can recognise perfect square trinomials by whether the middle term is twice the product of the square roots of the first and last terms.