SOLUTION: solve, using qudratic formula x(3x+7)-3x=0

Algebra ->  Algebra  -> Quadratic Equations and Parabolas -> SOLUTION: solve, using qudratic formula x(3x+7)-3x=0      Log On

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Question 41064: solve, using qudratic formula
x(3x+7)-3x=0
Answer by stanbon(48546) About Me  (Show Source):
You can put this solution on YOUR website!
x(3x+7)-3x=0
3x^2+7x-3x=0
3x^2+4x=0
a=3,b=4,c=0
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 3x%5E2%2B4x%2B0+=+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=%284%29%5E2-4%2A3%2A0=16.

Discriminant d=16 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-4%2B-sqrt%28+16+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%284%29%2Bsqrt%28+16+%29%29%2F2%5C3+=+0
x%5B2%5D+=+%28-%284%29-sqrt%28+16+%29%29%2F2%5C3+=+-1.33333333333333

Quadratic expression 3x%5E2%2B4x%2B0 can be factored:
3x%5E2%2B4x%2B0+=+3%28x-0%29%2A%28x--1.33333333333333%29
Again, the answer is: 0, -1.33333333333333. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+3%2Ax%5E2%2B4%2Ax%2B0+%29

Hope this helps.
Cheers,
Stan H.