Question 230820
 How do I solve for r where: 
(1/(1+r))*(30/r)-100 = 0 
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Multiply thru by r(1+r) to get:
(30)-100r(r+1) = 0
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-100r^2-100r+30 = 0
Divide thru by -10 to get:
10r^2 + 10r - 3 = 0
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Use the quadratic formula:
r = [-10 +- sqrt(100 - 4*10*-3)]/20
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r = [-10 +- sqrt(220)]/20
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r = [-10 +- 2sqrt(55)]/20
x = [-1/2 + (1/10)sqrt(55)] or x = [-1/2 + (1/10)sqrt(55)]
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Cheers,
Stan H.