Vertex form is f(x) = a(x - h)^2 + k. plugin -4 for f(x). leave the variable a. plugin 1 for x and 2 for h. Lastly, plug in 3 for k. Then slove the expression for a. Once you find a plug it in for the a variable, plug 2 in for the h and plug 3 in for the k.
