SOLUTION: 15x2+2x-8=0

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Question 106078: 15x2+2x-8=0
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

15x2%2B2x-8=0

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 15x%5E2%2B2x%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=%282%29%5E2-4%2A15%2A-8=484.

Discriminant d=484 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-2%2B-sqrt%28+484+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%282%29%2Bsqrt%28+484+%29%29%2F2%5C15+=+0.666666666666667
x%5B2%5D+=+%28-%282%29-sqrt%28+484+%29%29%2F2%5C15+=+-0.8

Quadratic expression 15x%5E2%2B2x%2B-8 can be factored:
15x%5E2%2B2x%2B-8+=+%28x-0.666666666666667%29%2A%28x--0.8%29
Again, the answer is: 0.666666666666667, -0.8. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+15%2Ax%5E2%2B2%2Ax%2B-8+%29