Question

What is the y coordinate of the vertex of y = − x^2 − 6x + 1

Answer 1

y = 10

Explanation:

The vertex coordinates of f(x) = ax² + bx + c is (h, k)

where:
`h=(-b)/(2a)\ ,\qquad k=f(h)`

f(x) = - x² - 6x + 1 ⇒ a = -1 b = -6

So:

`h=(-(-6))/(2(-1))=\frac6{-2}=-3\\\\y=f(h)=-(-3)^2-6(-3)+1=-9+18+1=10`