Question

What is the vertex of `y= -x^2+16x + 21`?

Answer 1

(8,85)

Explanation:

`(-b)/(2a)` gives the x coordinate for the vertex

`(-16)/(2xx-1)=(-16)/(-2)=8`

Put x=8 into the equation

`y=-8^2+16xx8+21`

`y=-64+128+21`

`y=85`