Question

What is the vertex of `y= -5x^2 + 8x - 13`?

Answer 1

`x=4/5,y=-49/5`

Explanation:

We get

`y'(x)=-10x+8` (to find the vertex coordinates)
`y'(x)=0` if `x=4/5`

now we compute the `y` coordinate:

`f(4/5)=-5*(16)/(25)+8*4/5-13=(32-16-65)/5=-49/5`