SOLUTION: 2x2 - 2x - 9 = 0

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Question 882527: 2x2 - 2x - 9 = 0
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
2x^2 - 2x - 9 = 0 format ax^2 + bx + c = 0
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B-2x%2B-9+=+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=%28-2%29%5E2-4%2A2%2A-9=76.

Discriminant d=76 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--2%2B-sqrt%28+76+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-2%29%2Bsqrt%28+76+%29%29%2F2%5C2+=+2.67944947177034
x%5B2%5D+=+%28-%28-2%29-sqrt%28+76+%29%29%2F2%5C2+=+-1.67944947177034

Quadratic expression 2x%5E2%2B-2x%2B-9 can be factored:
2x%5E2%2B-2x%2B-9+=+2%28x-2.67944947177034%29%2A%28x--1.67944947177034%29
Again, the answer is: 2.67944947177034, -1.67944947177034. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B-2%2Ax%2B-9+%29