The graph of a certain quadratic $y = ax^2 + bx + c$ is a parabola with vertex $(-4,0)$ which passes through the point $(1,-75)$. What is the value of $a$?
In vertex form we have that
y =a ( x + 4)^2 + 0
Since ( 1, -75) is on the graph, then
-75 = a ( 1 + 4)^2 + 0
-75 = a (5)^2
-75 = 25a
-75 / 25 = a = - 3
+501 
