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What is the value of x^5 ? (1)x^2 = 9 (2) x^3 > 9

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What is the value of x^5 ? (1)x^2 = 9 (2) x^3 > 9

by mitzwillrockgmat » Mon May 24, 2010 11:54 am
What is the value of x^5 ?
(1) x^2 = 9
(2) x^3 > 9

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

ok so i picked e but the answer is c. i dont see how but once again, pls explain :)

stat 1) x = + or - 3 insuff

stat 2) x is either > 2 or < -2 insuff

together, x can be + or - 3 then . hwo do i we get one concrete answer??
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by silencz » Mon May 24, 2010 12:05 pm
it can't be (-3) because if X was (-3), then (-3)^3>9, -27>9, incorrect, so answer is C, because statement 2 says that X is not (-3)
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by money9111 » Mon May 24, 2010 12:06 pm
answer is C because...

from statemnet 1 we know that x can either be 3 or -3
from statement 2 we know that x^3=9 so X must be positive

(3)^3 = 27 which is greater than 9
(-3)^3= -27 which is less than 9
Last edited by money9111 on Mon May 24, 2010 1:08 pm, edited 1 time in total.
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by jeffedwards » Mon May 24, 2010 12:46 pm
First let's look at the question x^5 =

We need to know the value of x, including if it's negative or positive, because x^5 will change depending on if x is negative or positive

1- Tells us x could be 3 or -3
2- Tells us that x is around 2.1 or higher and that it is positive (positive is key)

Neither alone is sufficient

Together we know that the answer is 3 because it's positive.
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