SOLUTION: Quadratic equation parabola.. y=3-15x-3x^2

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Question 982208: Quadratic equation parabola..
y=3-15x-3x^2
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
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y=-3x%5E2-15x%2B3
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Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case -3x%5E2%2B-15x%2B3+=+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=%28-15%29%5E2-4%2A-3%2A3=261.

Discriminant d=261 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--15%2B-sqrt%28+261+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-15%29%2Bsqrt%28+261+%29%29%2F2%5C-3+=+-5.19258240356725
x%5B2%5D+=+%28-%28-15%29-sqrt%28+261+%29%29%2F2%5C-3+=+0.192582403567252

Quadratic expression -3x%5E2%2B-15x%2B3 can be factored:
-3x%5E2%2B-15x%2B3+=+-3%28x--5.19258240356725%29%2A%28x-0.192582403567252%29
Again, the answer is: -5.19258240356725, 0.192582403567252. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-3%2Ax%5E2%2B-15%2Ax%2B3+%29

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Did you have a question about the parabola?