SOLUTION: use any method to solve the equation 7x^2-16x-28=0

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Question 307133: use any method to solve the equation 7x^2-16x-28=0
Answer by Stitch(470) About Me  (Show Source):
You can put this solution on YOUR website!
You can use the quadratic equatiion:
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 7x%5E2%2B-16x%2B-28+=+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=%28-16%29%5E2-4%2A7%2A-28=1040.

Discriminant d=1040 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--16%2B-sqrt%28+1040+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-16%29%2Bsqrt%28+1040+%29%29%2F2%5C7+=+3.44635935665673
x%5B2%5D+=+%28-%28-16%29-sqrt%28+1040+%29%29%2F2%5C7+=+-1.16064507094244

Quadratic expression 7x%5E2%2B-16x%2B-28 can be factored:
7x%5E2%2B-16x%2B-28+=+7%28x-3.44635935665673%29%2A%28x--1.16064507094244%29
Again, the answer is: 3.44635935665673, -1.16064507094244. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+7%2Ax%5E2%2B-16%2Ax%2B-28+%29