Math question, need solution please!

Question

(1 point) The parabola y=ax2+ky=ax2+k has vertex (0,−1)(0,−1) and passes through the point (4,2)(4,2). Find its equation.

Answer 1

y = a(x-h)^2 -k (h,k) = vertex

y= a(x-0)^2 -1 in vertex form (0,-1)

throught (4,2)

y=2, x=4

2=a(4)^2 -1

16a = 3

a= 3/16

y = (3/16)(x)^2 -1 is the quadratic equation with vertex (0,-1) and through the point (4,2)