The two roots are (-8,0) and (7,0)
So....we have this form
y = a ( x + 8) ( x - 7)
And since (2, 100) is on the graph, we can find "a" thusly :
100 = a(2 + 8) ( 2 - 7)
100 = a (10)(-5)
100 = -50a
100/-50 = a = - 2
So...the parabola is
y = -2 [ (x + 8) (x - 7) ]
y = -2 [ x^2 + x - 56 ]
y = -2x^2 - 2x + 112