Question

Write an equation for the quadratic graphed below

x-intercepts: (-1,0) and (2,0). y-intercept: (0,-3)

Answer 1

1/2(x + 1)(x - 2)

Explanation:

The x intercepts are -1 and 2, so the intercept form for this is y = a(x+1)(x-2).

We then by plug in the y intercept (0,-3)

-3 = a(0+1)(0-2)

1 * -2 = -2

-3 = -2a

division

-3/-2 = 3/2 which is 1.5

a = 1.5

y = 1.5(x+1)(x-2)

Answer 2

Explanation:

LOL The graph doesn’t match the y intercept :)

Anyway

If we have point (0,-3) we have a quadratic of

y=ax^2+bx-3 we are given points (-1,0) and (2,0) so

a-b-3=0 and 4a+2b-3=0

4a+2b-3+2(a-b-3)=0

4a+2b-3+2a-2b-6=0

6a-9=0

6a=9

a=1.5, since a-b=3

1.5-b=3

b=-1.5

y=1.5x^2-1.5x-3