SOLUTION: y^-2 + y^-1 = 20

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Question 678357: y^-2 + y^-1 = 20
Found 2 solutions by stanbon, Alan3354:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
y^-2 + y^-1 = 20
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Yours is a quadratic equation with variable y^-1
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(y^-1)^2 + y^-1 -20 = 0
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Quadratic Equation:
y^-1 = [-1 +- sqrt(1-4*-20)]/2
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y^-1 = [-1 +- 9]/2
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y^-1 = -5 or y^-1 = 4
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y = -1/5 or y = 1/4
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Cheers,
Stan H.
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Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
y^-2 + y^-1 = 20
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Multiply thru by y^2
1+%2B+y+=+20y%5E2
20y%5E2+-+y+-+1+=+0
((((5y + 1)*(4y - 1) = 0}}}
y = -1/5
y = 1/4