Question

What are the vertex and x-intercepts of the graph of the function below?

Answer 1

y= x^2 - 6x-7

Vertex = -b /2a

b= -6

a= 1

-(-6)/2(1)= 3

x= 3

Use the substitution method to find y

y= (3)^2-6(3)-7

(3)(3)-18-7

9-25

y= -16

Vertex is (3, 16)

Find x- intercept (y= 0)

y= x^2 - 6x-7

(x-7)(x+1)

x-7= 0

Move -7 to the other side. Sign changes from -7 to 7

x-7+7= 0+7

x= 7

x+1= 0

Move +1 to the other side. Sign changes from +1 to -1

x+1-1= 0-1

x= -1

Answer :B. Vertex: (3, -16); Intercepts: x=-1,7