SOLUTION: I don't know how to figure this problem out, please help. Solve each of the following quadratic equations. 4x^2 = 13x + 12

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: I don't know how to figure this problem out, please help. Solve each of the following quadratic equations. 4x^2 = 13x + 12      Log On


   

Question 44832: I don't know how to figure this problem out, please help.
Solve each of the following quadratic equations.
4x^2 = 13x + 12
Found 2 solutions by checkley71, kdturnage:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
4X~2-13X-12=O OR (4X+3)(X-4)=0 OR 4X=-3 OR X=-3/4 & X=4

Answer by kdturnage(4) 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 4x%5E2%2B-13x%2B-12+=+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=%28-13%29%5E2-4%2A4%2A-12=361.

Discriminant d=361 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--13%2B-sqrt%28+361+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-13%29%2Bsqrt%28+361+%29%29%2F2%5C4+=+4
x%5B2%5D+=+%28-%28-13%29-sqrt%28+361+%29%29%2F2%5C4+=+-0.75

Quadratic expression 4x%5E2%2B-13x%2B-12 can be factored:
4x%5E2%2B-13x%2B-12+=+4%28x-4%29%2A%28x--0.75%29
Again, the answer is: 4, -0.75. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+4%2Ax%5E2%2B-13%2Ax%2B-12+%29

-.075 can be written as -3/4