SOLUTION: Please help me find the solution to this problem rounded to the nearest hundredth: 7x^2-28x+15=0 The answers I got were, {0.64,3.36}

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Please help me find the solution to this problem rounded to the nearest hundredth: 7x^2-28x+15=0 The answers I got were, {0.64,3.36}      Log On


   

Question 850872: Please help me find the solution to this problem rounded to the nearest hundredth: 7x^2-28x+15=0
The answers I got were, {0.64,3.36}
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

{0.64,3.36} are Correct

 


 
Solved by pluggable solver: SOLVE quadratic equation with variable


Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 7x%5E2%2B-28x%2B15+=+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=%28-28%29%5E2-4%2A7%2A15=364.

  

  Discriminant d=364 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--28%2B-sqrt%28+364+%29%29%2F2%5Ca.

  

    x%5B1%5D+=+%28-%28-28%29%2Bsqrt%28+364+%29%29%2F2%5C7+=+3.36277028773849

    x%5B2%5D+=+%28-%28-28%29-sqrt%28+364+%29%29%2F2%5C7+=+0.637229712261506

    

    Quadratic expression 7x%5E2%2B-28x%2B15 can be factored:

  7x%5E2%2B-28x%2B15+=+7%28x-3.36277028773849%29%2A%28x-0.637229712261506%29

  Again, the answer is: 3.36277028773849, 0.637229712261506.
Here's your graph:

graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+7%2Ax%5E2%2B-28%2Ax%2B15+%29