SOLUTION: how do i factor 5x^2+12x-15

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Question 446676: how do i factor 5x^2+12x-15
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 5x%5E2%2B12x%2B-15+=+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=%2812%29%5E2-4%2A5%2A-15=444.

Discriminant d=444 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-12%2B-sqrt%28+444+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%2812%29%2Bsqrt%28+444+%29%29%2F2%5C5+=+0.907130750570548
x%5B2%5D+=+%28-%2812%29-sqrt%28+444+%29%29%2F2%5C5+=+-3.30713075057055

Quadratic expression 5x%5E2%2B12x%2B-15 can be factored:
5x%5E2%2B12x%2B-15+=+5%28x-0.907130750570548%29%2A%28x--3.30713075057055%29
Again, the answer is: 0.907130750570548, -3.30713075057055. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+5%2Ax%5E2%2B12%2Ax%2B-15+%29