SOLUTION: I am having a very hard time trying to figure this out. Can you please help me? Find the axis of symmetry. y = -x squared + 6x - 2

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: I am having a very hard time trying to figure this out. Can you please help me? Find the axis of symmetry. y = -x squared + 6x - 2      Log On


   

Question 123395: I am having a very hard time trying to figure this out. Can you please help me?
Find the axis of symmetry.
y = -x squared + 6x - 2
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
y=-x%5E2%2B6x-2
The quickest way is to get a piece of graph paper or use EXCEL to graph the function.
+graph%28+300%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C+-x%5E2%2B6x-2%29+
That's good but not exact.
The best way is to complete the square in x.
-x%5E2%2B6x%29
Take half of the x coefficient and square it.
c=%286%2F2%29%5E2=9
Be careful of the negative sign in front of the x square term.
You need to add -9 to complete the square.
-x%5E2%2B6x-9=-%28x-3%29%5E2
Add -9 to both sides of the equation.
y-9=-x%5E2%2B6x-9-2
y-9=-%28x-3%29%5E2-2
y=-%28x-3%29%5E2%2B7
As you can see the axis of symmetry is x=3.