SOLUTION: solve the following quadratic equation by using formula 3x²-4x-5=0 ? can I also be shown a checking method to show that my answer is correct

Algebra ->  Finance -> SOLUTION: solve the following quadratic equation by using formula 3x²-4x-5=0 ? can I also be shown a checking method to show that my answer is correct      Log On


   

Question 1029452: solve the following quadratic equation by using formula
3x²-4x-5=0 ?
can I also be shown a checking method to show that my answer is correct
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
solve the following quadratic equation by using formula
3x²-4x-5=0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 3x%5E2%2B-4x%2B-5+=+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%2A3%2A-5=76.

Discriminant d=76 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--4%2B-sqrt%28+76+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-4%29%2Bsqrt%28+76+%29%29%2F2%5C3+=+2.11963298118022
x%5B2%5D+=+%28-%28-4%29-sqrt%28+76+%29%29%2F2%5C3+=+-0.786299647846891

Quadratic expression 3x%5E2%2B-4x%2B-5 can be factored:
3x%5E2%2B-4x%2B-5+=+%28x-2.11963298118022%29%2A%28x--0.786299647846891%29
Again, the answer is: 2.11963298118022, -0.786299647846891. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+3%2Ax%5E2%2B-4%2Ax%2B-5+%29

===============

can I also be shown a checking method to show that my answer is correct
-----------
Sub the solutions in the equation.
It if's = 0, it's correct.