Question

The vertex of this parabola is at (3, -2). When the x-value is 4, the y-value is 3. What is the coefficient of the squared expression in the parabola's equation?

Answer 1

B. 5

Explanation:

You can fill in the given numbers in the vertex form equation and solve for the coefficient.

y = a(x -h)^2 +k

3 = a(4 -3)^2 -2

3 +2 = a·1 . . . add 2

5 = a

The coefficient of the squared expression is 5.

____

The offered x-value is 1 different from the vertex, so the value of that coefficient is the amount of change in the function. The function rises from -2 to +3, so has a change of 5 units. The coefficient is 5.