College Algebra (10th Edition)

$4x^2+12xy+9y^2$
RECALL: $(a+b)^2=a^2+2ab+b^2$ Use the formula with $a=2x$ and $b=3y$ to obtain: $(2x+3y)^2 \\= (2x)^2 + 2(2x)(3y) + (3y)^2 \\=4x^2+12xy+9y^2$