SOLUTION: Please help me solve this equation : -x^2 + 5x +4 = 0

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Question 1012983: Please help me solve this equation :
-x^2 + 5x +4 = 0
Found 2 solutions by ikleyn, macston:
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.
Please help me solve this equation :
-x^2 + 5x +4 = 0
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Use the quadratic formula, and you will get


x%5B1%2C2%5D = %28-5+%2B-+sqrt%2825+%2B+4%2A4%29%29%2F%28-2%29 = %285+%2B-+sqrt%2841%29%29%2F2.


Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
-x^2+5x+4=0
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case -1x%5E2%2B5x%2B4+=+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=%285%29%5E2-4%2A-1%2A4=41.

Discriminant d=41 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-5%2B-sqrt%28+41+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%285%29%2Bsqrt%28+41+%29%29%2F2%5C-1+=+-0.701562118716424
x%5B2%5D+=+%28-%285%29-sqrt%28+41+%29%29%2F2%5C-1+=+5.70156211871642

Quadratic expression -1x%5E2%2B5x%2B4 can be factored:
-1x%5E2%2B5x%2B4+=+-1%28x--0.701562118716424%29%2A%28x-5.70156211871642%29
Again, the answer is: -0.701562118716424, 5.70156211871642. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-1%2Ax%5E2%2B5%2Ax%2B4+%29