SOLUTION: How would you solve for x, using the quadratic formula? x^2+x-1=0 Thank you!

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Question 625481: How would you solve for x, using the quadratic formula?
x^2+x-1=0
Thank you!
Found 2 solutions by jim_thompson5910, oscargut:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2%2Bx-1=0 Start with the given equation.


Notice that the quadratic x%5E2%2Bx-1 is in the form of Ax%5E2%2BBx%2BC where A=1, B=1, and C=-1


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-%281%29+%2B-+sqrt%28+%281%29%5E2-4%281%29%28-1%29+%29%29%2F%282%281%29%29 Plug in A=1, B=1, and C=-1


x+=+%28-1+%2B-+sqrt%28+1-4%281%29%28-1%29+%29%29%2F%282%281%29%29 Square 1 to get 1.


x+=+%28-1+%2B-+sqrt%28+1--4+%29%29%2F%282%281%29%29 Multiply 4%281%29%28-1%29 to get -4


x+=+%28-1+%2B-+sqrt%28+1%2B4+%29%29%2F%282%281%29%29 Rewrite sqrt%281--4%29 as sqrt%281%2B4%29


x+=+%28-1+%2B-+sqrt%28+5+%29%29%2F%282%281%29%29 Add 1 to 4 to get 5


x+=+%28-1+%2B-+sqrt%28+5+%29%29%2F%282%29 Multiply 2 and 1 to get 2.


x+=+%28-1%2Bsqrt%285%29%29%2F%282%29 or x+=+%28-1-sqrt%285%29%29%2F%282%29 Break up the expression.


So the solutions are x+=+%28-1%2Bsqrt%285%29%29%2F%282%29 or x+=+%28-1-sqrt%285%29%29%2F%282%29
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Answer by oscargut(2103) About Me  (Show Source):
You can put this solution on YOUR website!

We have to solve: +x%5E2%2Bx-1=0+
(a = 1, b = 1, c = -1)
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-1+%2B-+sqrt%28+1%5E2-4%2A1%2A%28-1%29+%29%29%2F%282%2A1%29+
x+=+%28-1+%2B-+sqrt%28+5+%29%29%2F2+
Answer: x+=+%28-1+%2B+sqrt%28+5+%29%29%2F2+ , x+=+%28-1+-+sqrt%28+5+%29%29%2F2+

If you have any doubt or if you have more problems my e-mail is:
mthman@gmail.com