Question

What is the factored form of the expression k^2 - 9h^2

Answer 1

The equation which is supposed to help you is this one:
a^2 - b^2 = (a+b) (a-b)

So, what we need to do here is apply this equation:
k^2 - 9h^2 = 
k * k - (3h)^2 =
(k + 3h) (k - 3h)