Find the equation of a parabola whose vertex is at (−1, 7), whose axis of symmetry is x = −1, and whose y-intercept is (0, 20). Write your answer in vertex form.
+128408 We have the form
y = a ( x - h)^2 + k
(h,k) = the vertex = ( -1, 7)
So we have
y = a( x - -1)^2 + 7
y = a ( x + 1)^2 + 7
And the point (0,20) is on the graph so
20 = a ( 0 +1)^2 + 7
20 - 7 = a * 1^2
13 = a
The equation is
y = 13 ( x + 1)^2 + 7
Here's a graph : https://www.desmos.com/calculator/hnmgnpsmel
