Question

What is the y-value of the vertex of the function f(x) = –(x – 3)(x + 11)?

The y-value of the vertex is

Answer 1

49

Explanation:

Edge

Answer 2

The y-value of the vertex is 49

Explanation:

Given,
`f(x)=-(x-3)(x+11)`

`f(x)=-x^(2) -8x+33`

The vertex of the parabola
`y=ax^(2) +bx+c` occurs at
`x=(-b)/(2a)`.

For the given parabola,
`a=-1,b=-8,c=33`

So, vertex occurs at
`x=(-(-8))/(2(-1))=-4`

At this point
`f(x)=-(-4-3)(-4+11)=7*7=49`

∴ At vertex, y-value of
`f(x)=-(x-3)(x+11)` is 49.