SOLUTION: My question is graph the following equation: y = 2x(squared) - 8 how do i graph this...and how do i do the problem algebratically?

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Question 356823: My question is graph the following equation: y = 2x(squared) - 8
how do i graph this...and how do i do the problem algebratically?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B0x%2B-8+=+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=%280%29%5E2-4%2A2%2A-8=64.

Discriminant d=64 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-0%2B-sqrt%28+64+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%280%29%2Bsqrt%28+64+%29%29%2F2%5C2+=+2
x%5B2%5D+=+%28-%280%29-sqrt%28+64+%29%29%2F2%5C2+=+-2

Quadratic expression 2x%5E2%2B0x%2B-8 can be factored:
2x%5E2%2B0x%2B-8+=+%28x-2%29%2A%28x--2%29
Again, the answer is: 2, -2. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B0%2Ax%2B-8+%29