SOLUTION: how do you solve 60=[400/(1+r)^3]

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Question 41763: how do you solve 60=[400/(1+r)^3]
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Okay, from
60 = [400/(1+r)^3]
we can switch the 60 and the cube (by dividing both sides by 60 and multiplying both sides by the cube)...giving us
(1+r)^3 = 400/60
(1+r)^3 = 20/3
now take the cube root of both sides
1+r = cbrt(20/3)
r = cbrt(20/3) - 1
Now if you have to rationalize the denominator, multiply top and bottom by cbrt(9), giving us
r = [cbrt(180) / 3] - 1