Question

The vertex of this parabola is at (-5, -2). When the x-value is

-4, the
y-value is 2. What is the coefficient of the squared
expression in the parabola's equation?
-10
(-5,-2)
A. 4
B. 1
10
-10
C. 5
D. -1
10

Answer 1

A 4

Explanation:

the vertex form of a parabola is

y = a(x - h)² + k

with (h, k) being the vertex.

in our case

y = a(x - -5)² + -2 = a(x + 5)² - 2

we can calculate a by using the given point information.

the vertex itself does not help much, because it renders the x-term to 0.

so, we use the other given point (-4, 2) :

2 = a(-4 + 5)² - 2

4 = a(1)² = a