SOLUTION: x2-x-2=0 how to solve that

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Question 179905: x2-x-2=0 how to solve that
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2-x-2=0
You can factor this quadratic equation and solve for the zeros.
x%5E2-x-2=0
%28x-2%29%28x%2B1%29=0
First solution:
x-2=0
highlight%28+x=2%29
Second solution:
x%2B1=0
highlight%28+x=-1%29
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Here's a graph of the function to verify the solutions.

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You could also use the quadratic formula,
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
which is used to solve the general quadratic equation,
ax%5E2%2Bbx%2Bc=0
In your case,
a=1
b=-1
c=-2
Then,
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%2A1%2A%28-2%29+%29%29%2F%282%2A1%29+
x+=+%281+%2B-+sqrt%28+1%2B8+%29%29%2F%282%29+
x+=+%281+%2B-+sqrt%28+9%29%29%2F%282%29+
x+=+%281+%2B-+3%29%2F%282%29+
First solution:
x+=+%281+%2B+3%29%2F%282%29+
x+=+%284%29%2F%282%29+
highlight%28x=2%29
Second solution:
x+=+%281+-+3%29%2F%282%29+
x+=+%28-2%29%2F%282%29+
highlight%28x=-1%29