The graph of y=ax^2+bx+c is given below, where a, b, and c are integers. Find a-b+c.
1 and - 2 are roots and the point (0, -2) is on the graph
So
a ( 0 - 1) (0 + 2) = -2
a ( -1) ( 2) = -2
-2a = -2
a = 1
The parabola is
y = a ( x - 1) ( x + 2)
y = a ( x^2 + x - 2)
y = 1x^2 + 1x - 2
a + b + c = 1 + 1 - 2 = 0
