SOLUTION: My problem is:Identify the completing the squares, the vertex, the y-intercept and the axis of symmetry. 1. y=x^2+6x-11 2. y=3x^2-x+4 3. y=2x^2+7x-3 4. y=2x^2-8x-12 I need

Question 287399: My problem is:Identify the completing the squares, the vertex, the y-intercept and the axis of symmetry.
1. y=x^2+6x-11
2. y=3x^2-x+4
3. y=2x^2+7x-3
4. y=2x^2-8x-12
I need step by step answers
my email address is gdkpw@hotmail.com
Thank you
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
The best way to think of it is:
The axis of symmetry is where
is midway between the roots of the equation.
Then you find the vertex by plugging in
back into the equation to get , then
is the vertex.
An easy formula is: if the equation is in the form
, then the axis of symmetry is at

The y-intercept is at
---------------------------------------
I'll do your 1st problem:

The y-intercept is at
Now find roots:

The axis of symmetry is midway between the 2 roots which are:
root1 =
root2 =
is midway between these roots, so
is the axis of symmetry
And the simple formula gives the same answer:

Now plug this result back into the equation:

So, the vertex is at (-3,-20)
I'll plot the equation:

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