Find $a$ such that $ax^2+12x+9$ is the square of a binomial.

I've seen these questions before. If these are homework problems, this is not a homework site!

Hey Lightning, \(a=4\)

\(4x^2+12x+9\\ =(2x+3)^2\)

I used: \((x+y)^2=x^2+2xy+y^2\)

I saw the nine, so I know \(y=3\)

\(2xy=12\), and \(y=3\), so \(x=2\)

\(2^2=4, a=4\)

I hope this helped,

Gavin