SOLUTION: I am pushing in as a teacher aide the problem is the school has jumped me by about 2 yrs in my math...I just don't remember...Here is the problem -2x^2+8x+20=0

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Question 214675: I am pushing in as a teacher aide the problem is the school has jumped me by about 2 yrs in my math...I just don't remember...Here is the problem
-2x^2+8x+20=0
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Starting with:
-2x^2+8x+20=0
Multiply both sides by -1:
2x^2-8x-20=0
Divide both sides by 2:
x^2-4x-10=0
Always try to factor to find the answer first. In this case, it can't be factored so you must resort to the quadratic equation. Doing so yields:
x = {5.7412, -1.742}
.
Details of quadratic:
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-4x%2B-10+=+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=%28-4%29%5E2-4%2A1%2A-10=56.

Discriminant d=56 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--4%2B-sqrt%28+56+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-4%29%2Bsqrt%28+56+%29%29%2F2%5C1+=+5.74165738677394
x%5B2%5D+=+%28-%28-4%29-sqrt%28+56+%29%29%2F2%5C1+=+-1.74165738677394

Quadratic expression 1x%5E2%2B-4x%2B-10 can be factored:
1x%5E2%2B-4x%2B-10+=+1%28x-5.74165738677394%29%2A%28x--1.74165738677394%29
Again, the answer is: 5.74165738677394, -1.74165738677394. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-4%2Ax%2B-10+%29