SOLUTION: how do you write y=-4x^2+8x-1 in vertex form?

Question 151718: how do you write y=-4x^2+8x-1 in vertex form?
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
In order to write in vertex form, we need to complete the square.

Start with the right side.

Factor out the coefficient . This step is very important, the coefficient must be equal to 1.

Take half of the coefficient to get . In other words, .

Now square to get . In other words,

Now add and subtract inside the parenthesis. Make sure to place this after the "x" term. Notice how . So the expression is not changed.

Group the first three terms.

Factor to get .

Combine like terms.

Distribute.

Multiply.

So after completing the square, transforms to . So .

So is equivalent to .

So the expression is now in vertex form where , and .

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