# How do you write f(x)= 6x-x^2 in vertex form?

Apr 9, 2018

The general vertex form is $y = a {\left(x - h\right)}^{2} + k$ where $\left(h , k\right)$ is the vertex.

#### Explanation:

$f \left(x\right) = 6 x - {x}^{2}$
$f \left(x\right) = - {x}^{2} + 6 x - 9 + 9$
$f \left(x\right) = - \left({x}^{2} - 6 x + 9\right) - 9$

Vertex form:
$f \left(x\right) = - {\left(x - 3\right)}^{2} - 9$

Vertex:
$\left(3 , - 9\right)$