Question

What is the equation of the parabola with vertex (-2,5) and an x-intercept of x = 3

Answer 1

Step-by-step explanation:

if parabola has a vertex not in x-axis, it should have 2 x intercept

x-vertex = -2

first x intercept = 3

second x intercept should -7

so the equation will like this

y = a(x-x1)(x-x2)

y = a (x-3)(x+7)

y = a(x² + 4x - 21)

5 = a((-2)² + 4(-2) - 21)

5 = a(4 - 8 - 21)

5 = a(-25)

a = 5/(-25)

a = -1/5

then the equation is

y = (-1/5)(x² - 4x - 21)

or you can write as

y = -x²/5 + 4x/5 + 21/5

or as this one

5y = -x² + 4x + 21