Find the coordinates of the vertex

Question

Find the coordinates of the vertex and the intercepts of the following quadratic function. When necessary, approximate the x-intercepts to the nearest tenth. f(x)=xsquare2 + 8x+7

Answer 1

f(x) = x² + 8x + 7 = (x + 7)(x + 1)

 

The x intercepts are -7 and -1.

 

The x-coordinate of the vertex is

 

-b/(2a) = -8/[2(1)] = -4

 

The y coordinate of the vertex is f(-4) = (-4)² + 8(-4) + 7 = 16 - 32 + 7 = -9