What is the y-value of the vertex 4x^2 +8x-8

-12

Step-by-step explanation:

Here the coefficients a, b and c are 4, 8 and -8 respectively.

                                                                     -b

A formula for the axis of symmetry is x =

                                                                      2a

                                 -8

... which yields x = = -1

                                2(4)

Evaluating f(x) = 4x^2 + 8x - 8 at x = -1 yields   f(-1) = 4(-1)^2 + 8(-1) - 8 = -12.

The y-value of the vertex is -12.  Note that the vertex lies right smack on the axis of symmetry.

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9

the correct option is b

step-by-step explanation: