SOLUTION: I am having some trouble graphing this eqaution: y=x^2-2x-8 The question asks that I find the y and x intercepts and the vertex. I got the x intercepts at 4 and-2, the y intercept

Question 144744: I am having some trouble graphing this eqaution: y=x^2-2x-8
The question asks that I find the y and x intercepts and the vertex. I got the x intercepts at 4 and-2, the y intercept at 0,-8 and the vertex at -1,-7. The vertex doesnt seem to work though. I'd appreciate any help I could get.
~Kyle
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Everything is correct except for the vertex

To find the vertex, we first need to find the axis of symmetry (ie the x-coordinate of the vertex)
To find the axis of symmetry, use this formula:

From the equation we can see that a=1 and b=-2

Plug in b=-2 and a=1

Negate -2 to get 2

Multiply 2 and 1 to get 2

Reduce

So the axis of symmetry is

So the x-coordinate of the vertex is . Lets plug this into the equation to find the y-coordinate of the vertex.

Lets evaluate

Start with the given polynomial

Plug in

Raise 1 to the second power to get 1

Now combine like terms

So the vertex is (1,-9)

So let's use the this (along with the other pieces you solved for) to graph
Graph of
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