Question

What are the vertex and xintercepts of the graph of the function below?
y=(x + 4)(x-2)

Answer 1

Yo sup??

y=(x+4)(x-2)

to find the x intercept put y=0

0=(x+4)(x-2)

so either x=-4 or x=2

Therefore the graph intersects the x axis at -4 and 2

Lenght of x intercept=|-4-2|=6 units

y=(x+4)(x-2)

=x^2+2x-8

This is an upward opening parabola

To find the coordinates of the vertex we can apply the formula

(-b/2a,-D/4a)

b=2

a=1

D=b^2-4ac

=4-4*1*(-8)

=4+32=36

Vertex=(-2/2*1,-36/4*1)

=(-1,-9)

Hope this helps.