Negative exponents

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diegocuenca: Senior | Next Rank: 100 Posts; Posts: 32; Joined: Thu Feb 24, 2011 1:17 pm

by diegocuenca » Sun Aug 14, 2011 3:34 pm

This is from a BTG practice question

Is x < y ?

(1) y = x^-3

(2) x < 0

2. Nothing about y, NS
1. I'm confused on this one, how would x look as a fraction? If it were x^-1 then it would be 1/x?

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Source: Beat The GMAT — Data Sufficiency | Sun Aug 14, 2011 3:34 pm

gmatboost: Master | Next Rank: 500 Posts; Posts: 312; Joined: Tue Aug 02, 2011 3:16 pmFollowed by: 33 members; Location: New York City; Thanked: 130 times; GMAT Score:780

by gmatboost » Mon Aug 15, 2011 10:11 am

Not sure if this answers your q exactly but y = x^(-3) means y = 1/(x^3)

In your table you have ignored negative fraction x values like -1/2. It worked out okay since the question was x < y, but if the question had been x <= y you may have been in trouble.

x = -1/2 -> y = -8
x = -2 -> y = -1/8

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