SOLUTION: i have no idea how to even begin this problem. Any help is appreciated! Use the quadratic formula to determine the x-intercepts (if any) of the following function. Then evalu

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: i have no idea how to even begin this problem. Any help is appreciated! Use the quadratic formula to determine the x-intercepts (if any) of the following function. Then evalu      Log On


   

Question 209617: i have no idea how to even begin this problem. Any help is appreciated!
Use the quadratic formula to determine the x-intercepts (if any) of the following function. Then evaluate the function for several values of x, and use the resulting points to graph the function.

f(x) = -2x2 + 2x - 9
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
f(x) = -2x2 + 2x - 9
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Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case -2x%5E2%2B2x%2B-9+=+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%2A-2%2A-9=-68.

The discriminant -68 is less than zero. That means that there are no solutions among real numbers.

If you are a student of advanced school algebra and are aware about imaginary numbers, read on.


In the field of imaginary numbers, the square root of -68 is + or - sqrt%28+68%29+=+8.24621125123532.

The solution is , or
Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-2%2Ax%5E2%2B2%2Ax%2B-9+%29

No x intercepts.