SOLUTION: Solve x^2 +18x+ 4=0

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Question 151207: Solve x^2 +18x+ 4=0
Found 2 solutions by jim_thompson5910, jojo14344:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2B18x%2B4=0 Start with the given equation.


Notice we have a quadratic equation in the form of ax%5E2%2Bbx%2Bc where a=1, b=18, and c=4


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-%2818%29+%2B-+sqrt%28+%2818%29%5E2-4%281%29%284%29+%29%29%2F%282%281%29%29 Plug in a=1, b=18, and c=4


x+=+%28-18+%2B-+sqrt%28+324-4%281%29%284%29+%29%29%2F%282%281%29%29 Square 18 to get 324.


x+=+%28-18+%2B-+sqrt%28+324-16+%29%29%2F%282%281%29%29 Multiply 4%281%29%284%29 to get 16


x+=+%28-18+%2B-+sqrt%28+308+%29%29%2F%282%281%29%29 Subtract 16 from 324 to get 308


x+=+%28-18+%2B-+sqrt%28+308+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-18+%2B-+2%2Asqrt%2877%29%29%2F%282%29 Simplify the square root (note: If you need help with simplifying square roots, check out this solver)


x+=+%28-18%29%2F%282%29+%2B-+%282%2Asqrt%2877%29%29%2F%282%29 Break up the fraction.


x+=+-9+%2B-+sqrt%2877%29 Reduce.


x+=+-9%2Bsqrt%2877%29 or x+=+-9-sqrt%2877%29 Break up the expression.


So our answers are x+=+-9%2Bsqrt%2877%29 or x+=+-9-sqrt%2877%29


which approximate to x=-0.225 or x=-17.775

Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!
given x%5E2%2B18x%2B4=0 by quadratic formula:
a=1, b=18, & c=4
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F2a
x=%28-18%2B-sqrt%2818%5E2-4%2A1%2A4%29%29%2F2%2A1
x=%28-18%2B-sqrt%28324-16%29%29%2F2
x=%28-18%2B-17.55%29%2F2
x=-0.225
x=-17.775
Check these 2 values of 'x' with the above eqn and you'll get zero.
Thank you,
Jojo