SOLUTION: Very stuck, please help me please Solve {{{ x^2+18x-4=0 }}} The solution is x = ???

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Very stuck, please help me please Solve {{{ x^2+18x-4=0 }}} The solution is x = ???      Log On


   

Question 359581: Very stuck, please help me please
Solve
+x%5E2%2B18x-4=0+

The solution is x = ???
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
+x%5E2%2B18x-4=0+
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B18x%2B-4+=+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=%2818%29%5E2-4%2A1%2A-4=340.

Discriminant d=340 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-18%2B-sqrt%28+340+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%2818%29%2Bsqrt%28+340+%29%29%2F2%5C1+=+0.219544457292887
x%5B2%5D+=+%28-%2818%29-sqrt%28+340+%29%29%2F2%5C1+=+-18.2195444572929

Quadratic expression 1x%5E2%2B18x%2B-4 can be factored:
1x%5E2%2B18x%2B-4+=+1%28x-0.219544457292887%29%2A%28x--18.2195444572929%29
Again, the answer is: 0.219544457292887, -18.2195444572929. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B18%2Ax%2B-4+%29