SOLUTION: I need help on solving this step by step , i don't know how to go about this problem when it has fractions. Find the real solutions of the equation. x2/3 - 2x1/3 - 15 = 0

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Question 411649: I need help on solving this step by step , i don't know how to go about this problem when it has fractions.
Find the real solutions of the equation.
x2/3 - 2x1/3 - 15 = 0
Answer by emargo19(101) About Me  (Show Source):
You can put this solution on YOUR website!
x2/3 - 2x1/3 - 15 = 0
%28x%5E2%291/3 - 2x1/3 - 15 = 0
Let x1/3=u
Therefore the equation is u%5E2-2u-15=0
u%5E2%2B3u-5u-15=0
u%28u%2B3%29-5%28u%2B3%29=0
%28u-5%29%28u%2B3%29=0
u-5=0 or u%2B3=0
u=5 or u=-3