Algebra II

Question

Find the vertex of the parabola with the equation f(x) = 2x2 + 8x + 9.

1) (1, -2)

2) (2, -1)

3) (-1, 2)

4) (-2, 1)

Answer 1

 

 

Hi Carrie,

 

Algebra II
Find the vertex of the parabola with the equation f(x) = 2x² + 8x + 9.

1) (1, -2)

2) (2, -1)

3) (-1, 2)

4) (-2, 1)

 

The axis of symmetry for a quadratic equation is a vertical line and uses the x-coordinate of the vertex.

The x-coordinate of the vertex can be found using the formula
x=-b
    ---
    2a

for f(x) = 2x² + 8x + 9

a=2
b=8
c=9

 

x=  -8

    -----

     2(2)

x=-8/4

x=-2

 

To calculate the y-value of the vertex, substitute the x-value into the original equation.

f(x) = 2x² + 8x + 9

f(-2) = 2(-2)² + 8(-2) + 9

       = 2(4)-16+9

       = 8-16+9

       =1

 

ANSWER:  the Vertex is (-2,1) which is response #4.

 

Hope this helps you Carrie.