Write an equation of the parabola in intercept form (-1,0) (2,0) (1,-2)

Question

I don't understand this can someone help me

Answer 1

Intercept form

y = a(x-p)(x-q)

The two intercepts are -1 and 2 (for points -1, 0 and 2,0):

so equation becomes:

y = a(x+ 1)(x-2)

to solve for a, plug in (1,-2)

-2 = a(1 + 1)(1 - 2)

-2 = -2a

a = 1

equations is

y = (x+1)(x-2)