exponents

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J N: Senior | Next Rank: 100 Posts; Posts: 44; Joined: Tue Mar 12, 2013 2:27 pm; Thanked: 3 times

exponents

by J N » Thu May 23, 2013 11:51 am

from veritas (problem 56 book 4 pg 189)

making a silly mistake somewhere

if 5 * (125)^(1/3) = 1 / (5^(1/x)) then x=?

5*5*5^(1/x) = 1

5^(1+1+(1/x)) =1

2 +(1/x) = 0

x= -1/2

answer is -4

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Source: Beat The GMAT — Problem Solving | Thu May 23, 2013 11:51 am

mkdureja: Senior | Next Rank: 100 Posts; Posts: 38; Joined: Fri Jan 04, 2013 12:55 am; Thanked: 11 times

by mkdureja » Thu May 23, 2013 11:44 pm

J N wrote:from veritas (problem 56 book 4 pg 189)

making a silly mistake somewhere

if 5 * (125)^(1/3) = 1 / (5^(1/x)) then x=?

5*5*5^(1/x) = 1

5^(1+1+(1/x)) =1

2 +(1/x) = 0

x= -1/2

answer is -4

-1/2 is correct