SOLUTION: graph 3x^2 -x -7 =0

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Question 345387: graph 3x^2 -x -7 =0
Found 2 solutions by ichudov, ewatrrr:
Answer by ichudov(507) About Me  (Show Source):
You can put this solution on YOUR website!
Just use the graphing solver.
graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+3x%5E2+-x+-7+%29+

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
Hi,
3x%5E2+-x+-7+=0
.
Using the Quadratic Formula to solve for x and graph the equation:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
.
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 3x%5E2%2B-1x%2B-7+=+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=%28-1%29%5E2-4%2A3%2A-7=85.

Discriminant d=85 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--1%2B-sqrt%28+85+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-1%29%2Bsqrt%28+85+%29%29%2F2%5C3+=+1.70325740954881
x%5B2%5D+=+%28-%28-1%29-sqrt%28+85+%29%29%2F2%5C3+=+-1.36992407621548

Quadratic expression 3x%5E2%2B-1x%2B-7 can be factored:
3x%5E2%2B-1x%2B-7+=+3%28x-1.70325740954881%29%2A%28x--1.36992407621548%29
Again, the answer is: 1.70325740954881, -1.36992407621548. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+3%2Ax%5E2%2B-1%2Ax%2B-7+%29