Rewrite the equation in term of and .

Complete the square for .

Use the form , to find the values of , , and .

Consider the vertex form of a parabola.

Substitute the values of and into the formula .

Simplify the right side.

Cancel the common factor of and .

Factor out of .

Move the negative one from the denominator of .

Multiply by .

Find the value of using the formula .

Simplify each term.

Cancel the common factor of and .

Factor out of .

Move the negative one from the denominator of .

Multiply by .

Multiply by .

Add and .

Substitute the values of , , and into the vertex form .

Set equal to the new right side.

Use the vertex form, , to determine the values of , , and .

Find the vertex .

Find the Vertex f(x)=-x^2+4x-9