Question

What is the equation written in vertex form of a parabola

with a vertex of (9, -1) that passes through (7, 7)?

Answer 1

y = 2(x - 9)² - 1

Explanation:

The equation of a parabola in vertex form is

y = a(x - h)² + k

where (h, k) are the coordinates of the vertex and a is a multiplier

Here (h, k ) = (9, - 1 ) , thus

y = a(x - 9)² - 1

To find a substitute (7, 7 ) into the equation

7 = a(7 - 9)² - 1 ( add 1 to both sides )

8 = 4a ( divide both sides by 4 )

2 = a , then

y = 2(x - 9)² - 1