SOLUTION: x to the second power +8x+5=0

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Question 189241: x to the second power +8x+5=0
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2B8x%2B5=0 Start with the given equation.


Notice we have a quadratic equation in the form of ax%5E2%2Bbx%2Bc where a=1, b=8, and c=5


Let's use the quadratic formula to solve for x


x+=+%28-b+%2B-+sqrt%28+b%5E2-4ac+%29%29%2F%282a%29 Start with the quadratic formula


x+=+%28-%288%29+%2B-+sqrt%28+%288%29%5E2-4%281%29%285%29+%29%29%2F%282%281%29%29 Plug in a=1, b=8, and c=5


x+=+%28-8+%2B-+sqrt%28+64-4%281%29%285%29+%29%29%2F%282%281%29%29 Square 8 to get 64.


x+=+%28-8+%2B-+sqrt%28+64-20+%29%29%2F%282%281%29%29 Multiply 4%281%29%285%29 to get 20


x+=+%28-8+%2B-+sqrt%28+44+%29%29%2F%282%281%29%29 Subtract 20 from 64 to get 44


x+=+%28-8+%2B-+sqrt%28+44+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-8+%2B-+2%2Asqrt%2811%29%29%2F%282%29 Simplify the square root (note: If you need help with simplifying square roots, check out this solver)


x+=+%28-8%29%2F%282%29+%2B-+%282%2Asqrt%2811%29%29%2F%282%29 Break up the fraction.


x+=+-4+%2B-+sqrt%2811%29 Reduce.


x+=+-4%2Bsqrt%2811%29 or x+=+-4-sqrt%2811%29 Break up the expression.


So the answers are x+=+-4%2Bsqrt%2811%29 or x+=+-4-sqrt%2811%29


which approximate to x=-0.683 or x=-7.317