we know that the graph passes through these points:

(50,0), (-50,0), (10, 40), (-10,40)

so...subbing x and y coordinates:

0 = a/50^2 + b

40 = a/10^2 + b

0 = a + 2500b..[1]

4000= a +100b..[2]

[2]-[1]:

4000 = -2400 b

b = -5/3

so a = 2500*5/3 = 12500/3

hope these correlate to the answers, these numbers look weird.