Is x 0 ?

Question

Is x > 0 ?

(1) x < x^2 
(2) x < x^3

Bunuel · Answer

Is x > 0 (1) x < x^2 --> x*(x-1)>0 --> x<0 or x>1. Not sufficient. (2) x < x^3 --> (x+1)*x*(x-1)>0 --> -11. Not sufficient. (1)+(2) Intersection of the ranges from (1) and (2) is -11. Not sufficient. Answer: E.

rxs0005 · Answer

Bunuel in S1 why did u consider this as x< 0 i took this as x >0 and x-1 > 0

Bunuel · Answer

x*(x-1)>0 --> either both multiples are positive or both negative: x>0 and x-1>0, x>1 --> so x>1; x<0 and x-1<0, x<1 --> so x<0; Thus x*(x-1)>0 holds true for x<0 and x>1. Check for more here: x2-4x-94661.html#p731476 or here: inequalities-trick-91482.html Similar questions: gmat-quant-rev-2nd-ed-ds-104280.html inequality-98674.html ds-algebra-107401.html

rxs0005 · Answer

thanks for the prompt reply i now get it

thesfactor · Answer

Answer is E because:
statement 1 says x can be either a negative fraction OR a positive integer
Statement 2 says x can be either a positive fraction OR a negative integer...

subhashghosh · Answer

(1)

x can be -ve (fraction or integer) or +ve (but not a +ve fraction), so not enough

(2)

x can be -ve fraction , say -1/2 or a +ve number > 1 so not enough.

Again, from (1) and (2), x can be a -ve fraction or +ve number, so not enough.

Answer is E.

Eden · Answer

Hi
 How does one solve this question using Gupreet's method?
 I was able to do the first statement but I dont know how to draw the root of x^2(x-1)>0. Thanks

menacel · Answer

who is gurpeet?

the second should be

0>x^3-x

factor an x out

0> x(x^2-1)
0>x(x+1)(x-1)

amit2k9 · Answer

region on number scale

x>0 and -0.1<= x <= 0. satisfies both.

E

GuptaDarsh · Answer

Bunuel : " x < x^3 --> (x+1)*x*(x-1)>0 --> -11. Not sufficient." i could not understand the concept of Roots of 3rd degree quad equation can you please explain.. Thnaks in advance

cheers

Bunuel · Answer

This explained here: inequalities-trick-91482.html data-suff-inequalities-109078.html range-for-variable-x-in-a-given-inequality-109468.html everything-is-less-than-zero-108884.html graphic-approach-to-problems-with-inequalities-68037.html

bumpbot · Answer

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Is x > 0 ?

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GMAT Data Sufficiency (DS) Questions

Is x > 0 ?

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