SOLUTION: x^2+18x-4=0 solve for x

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Question 330169: x^2+18x-4=0 solve for x
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
x^2+18x-4=0
compare it with the general equation
ax^2 +bx +c
a=1, b=18, c=-4
x1,x2 the roots of the equation are
x1+=+%28-b+%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
.
plug the values of a,b,c in the equation.
x1=%28-%2818%29%2Bsqrt%28%2818%29%5E2-4%2A1%2A%28-4%29%29%29%2F%282%2A1%29
x1=-18%2Bsqrt%28324%2B16%29%2F%282%29
x1=+%28-18%2Bsqrt%28340%29%29%2F%282%29
x1=%28-18%2B2%2Asqrt%2885%29%29%2F%282%29
x1=%282%2A%28-9%2Bsqrt%2885%29%29%29%2F2
x1=%28-9%2Bsqrt85%29
...
x2=%28-9-sqrt85%29