SOLUTION: Answer the questions about the given function f(x)=-15x^2-17x if f(x)=-2 what is x?

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Question 468054: Answer the questions about the given function
f(x)=-15x^2-17x
if f(x)=-2 what is x?
Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
-15x2-17x=-2
-15x2-17x+2=0
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case -15x%5E2%2B-17x%2B2+=+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=%28-17%29%5E2-4%2A-15%2A2=409.

Discriminant d=409 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--17%2B-sqrt%28+409+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-17%29%2Bsqrt%28+409+%29%29%2F2%5C-15+=+-1.24079161387189
x%5B2%5D+=+%28-%28-17%29-sqrt%28+409+%29%29%2F2%5C-15+=+0.107458280538556

Quadratic expression -15x%5E2%2B-17x%2B2 can be factored:
-15x%5E2%2B-17x%2B2+=+-15%28x--1.24079161387189%29%2A%28x-0.107458280538556%29
Again, the answer is: -1.24079161387189, 0.107458280538556. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-15%2Ax%5E2%2B-17%2Ax%2B2+%29