What is the vertex of y= x^2-x-16+(x-1)^2?

1 Answer
Dec 13, 2017

First, expand the expression and combine like terms:

x^2-x-16+(x-1)^2

\implies x^2-x-16+(x^2-2x+1)

\implies x^2+x^2-x-2x-16+1

\implies 2x^2-3x-15

Now that's in the form ax^2+bx+c, the vertex's x-coordinate is \frac{-b}{2a}.

\implies \frac{3}{4}

Plug that into the original equation to find the y-coordinate:

2x^2-3x-15

\implies 2(3/4)^2-3(3/4)-15

\implies 9/8-9/4-15/1

implies -16.125

I'm in class rn and will finish this later. Sorry. :/