Write the equation for the parabola that has x− intercepts (−2,0) and (1.2,0) and y− intercept (0,−4).

Answer 1

y = k(x-p)(x-q) is zero at x = p and at x = q, therefore p=-2 and q = 1.2
so
y =k (x+2)(x-1.2) = k (x^2 + .8 x - 2.4)
when x = 0, y = -4
-4 = -2.4 k
k = 1 2/3 = 5/3
y = (5/3) (x^2 + .8 x - 2.4)