line of symmetry is x = -b / 2a = -1, so b = 2a.

x = -2 is a zero and just 1 left of line of symmetry, so other zero must be 1 right of line of symmetry at x = 0.

finally, (-2,0) is 1 left but 5 up from min (-1,-5), so vertical stretch is 5 = a.

so 5x(x + 2) = 5x² + 10x, a = 5, b = 10, c = 0