SOLUTION: PLEASE HELP ME SOLVE THIS EQUATION FOR THE AXIS OF SYMMETRY: X^2-6X-7 THANKYOU:D

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Question 444561: PLEASE HELP ME SOLVE THIS EQUATION FOR THE AXIS OF SYMMETRY: X^2-6X-7 THANKYOU:D
Answer by chriswen(106) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-6x%2B-7+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-6%29%5E2-4%2A1%2A-7=64.

Discriminant d=64 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--6%2B-sqrt%28+64+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-6%29%2Bsqrt%28+64+%29%29%2F2%5C1+=+7
x%5B2%5D+=+%28-%28-6%29-sqrt%28+64+%29%29%2F2%5C1+=+-1

Quadratic expression 1x%5E2%2B-6x%2B-7 can be factored:
1x%5E2%2B-6x%2B-7+=+1%28x-7%29%2A%28x--1%29
Again, the answer is: 7, -1. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-6%2Ax%2B-7+%29


After you solve you get 7 and -1.
(7+-1)/2=3
This is the midpoint between both numbers. The axis of symmetry is 3.