The graph of a certain quadratic y=ax2+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
+502 
