What are the vertex and x-intercepts of the graph of the function below?
y = x2 - 4x - 21
a. vertex: (2, -25); intercepts: x = 3, -7
b. vertex: (2, 17); intercepts: x = -3, 7
c. vertex: (2, 17); intercepts: x = 3, -7
d. vertex: (2, -25); intercepts: x = -3, 7

I think is D.vertex(2_25);intercept:x=_3,7

Vertex: (2, -25); Intercepts: x = -3, 7

Step-by-step explanation:

Lets find out the vertex and the x intercepts

To find out the vertex we use formula

The value of a= 1, b=-4. Plug in the values

Substitute x=2 and find out y

So vertex (2,-25)

Now we find out x intercepts, replace y with 0 and solve for x

we find out two factors whose product -21 and add upto -4

the factors are -7 and 3

x intercepts are -3,7

do i do it on a graph?

step-by-step explanation:

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12