SOLUTION: Solve. Round results to the nearest thousandth. 7x^2 - 6x - .4255 = 0

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Question 173805This question is from textbook Introductory Algebra
: Solve. Round results to the nearest thousandth.
7x^2 - 6x - .4255 = 0 This question is from textbook Introductory Algebra

Answer by vleith(2983) 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 7x%5E2%2B-6x%2B-0.4255+=+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=%28-6%29%5E2-4%2A7%2A-0.4255=47.914.

Discriminant d=47.914 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--6%2B-sqrt%28+47.914+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-6%29%2Bsqrt%28+47.914+%29%29%2F2%5C7+=+0.922999566599059
x%5B2%5D+=+%28-%28-6%29-sqrt%28+47.914+%29%29%2F2%5C7+=+-0.0658567094562017

Quadratic expression 7x%5E2%2B-6x%2B-0.4255 can be factored:
7x%5E2%2B-6x%2B-0.4255+=+7%28x-0.922999566599059%29%2A%28x--0.0658567094562017%29
Again, the answer is: 0.922999566599059, -0.0658567094562017. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+7%2Ax%5E2%2B-6%2Ax%2B-0.4255+%29


Rounded 0.923 and -0.066