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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
can you please explain it in detail?

Economist wrote:
The expression can be rephrased as : Is 1/x > x ?
stmt 1. The expression is true for x < 0 except x=-1. But there is no restriction on x. So insuff.
stmt 2. Value of n does not matter.

combining , still the same question, can x be -1 ( and also be < 0 )?
Hence E.
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
x^(n+1) = x^n.x

Now, while reducing the given inequality we need to take care of the inequality sign. ONLY if a -ve value is multiplied/divided on BOTH sides of the equation we need to reverse the inequality.

But, in this case we are not multiplying or dividing each side. We are just canceling out the same factor(-ve or +ve) from each side. So the inequality will remain the same.

In other words, x^n/x^n = 1, regardless of the sign of x^n. So, basically we are just multiplying each side by 1 :)
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
Economist wrote:
The expression can be rephrased as : Is 1/x > x ?
stmt 1. The expression is true for x < 0 except x=-1. But there is no restriction on x. So insuff.
stmt 2. Value of n does not matter.

combining , still the same question, can x be -1 ( and also be < 0 )?
Hence E.


Is it only for x= -1 or for the range -1<x<0?
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
+1 E

When we simplify the original inequality, using exponents theory, we get 1/x > x.

So both statements are insufficient.
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
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Bunuel wrote:
Ranges in above solutions are not correct.

Is \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)?

First of all realistic GMAT question would mention that \(x\neq{0}\).

Anyway: is \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)? --> is \(x^{n-n-1}<x^{n+1-n}\)? --> is \(\frac{1}{x}<x\)? --> is \(x-\frac{1}{x}>0\)? --> is \(\frac{x^2-1}{x}>0\)? --> is \(\frac{(x-1)(x+1)}{x}>0\)? So the question basically asks is \(-1<x<0\) or \(x>1\). (For more on this check: i-have-been-trying-to-understand-inequalities-by-reading-110917.html or range-for-variable-x-in-a-given-inequality-109468.html) Also noitce that the value of n is irrelevant to answer the question.

(1) x < 0. Not sufficient.

(2) n < 0. Not sufficient.

(1)+(2) Still can not answer the question. Not sufficient.

Answer: E.


Why have we flipped the inequality sign here? \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)? --> is \(x^{n-n-1}<x^{n+1-n}\)?
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
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emailmkarthik wrote:
Bunuel wrote:
Ranges in above solutions are not correct.

Is \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)?

First of all realistic GMAT question would mention that \(x\neq{0}\).

Anyway: is \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)? --> is \(x^{n-n-1}<x^{n+1-n}\)? --> is \(\frac{1}{x}<x\)? --> is \(x-\frac{1}{x}>0\)? --> is \(\frac{x^2-1}{x}>0\)? --> is \(\frac{(x-1)(x+1)}{x}>0\)? So the question basically asks is \(-1<x<0\) or \(x>1\). (For more on this check: i-have-been-trying-to-understand-inequalities-by-reading-110917.html or range-for-variable-x-in-a-given-inequality-109468.html) Also noitce that the value of n is irrelevant to answer the question.

(1) x < 0. Not sufficient.

(2) n < 0. Not sufficient.

(1)+(2) Still can not answer the question. Not sufficient.

Answer: E.


Why have we flipped the inequality sign here? \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)? --> is \(x^{n-n-1}<x^{n+1-n}\)?


It was a typo edited. Thank you. +1.
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
tejal777 wrote:
Is x^n/x^(n+1)>x^(n+1)/x^n?

(1) x < 0

(2) n < 0


The correct answer is E

From question stem we can simplify and get is 1/x > x?

1/x - x > 0 --> Using key points is x<-1 or 0<x<1?

Statement 1

x<0 not sufficient

Statement 2

I don't care about 'n' at this point

Statements 1 and 2 together

I still don't have enough info

Hence E

Hope it helps
Cheers!

J :)
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
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tejal777 wrote:
Is x^n/x^(n+1)>x^(n+1)/x^n?

(1) x < 0

(2) n < 0


Sol: Given question can be rephrased as is 1/x>x ------> (1-x^2)/x>0

Given x<0, let x=-2 then the above equation holds true but if x= -1/2 then the equation doesn't hold true
(1-1/4)/-1/2 ------>3/4/-1/2---->-6/4 or -3/2 which is less than 0
Ans Statement A is not sufficient

A and D ruled out

St2: given n<0 -----> There is no use for it. Hence B ruled out
With both statements we still don't have anything new.

Hence Ans E
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
Expert Reply
Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.



Is x^n/x^(n+1)>x^(n+1)/x^n?

(1) x < 0

(2) n < 0

==>transforming the original condition and the question by variable approach method, we have x^n/x^(n+1)>x^(n+1)/x^n? --> 1/x>x?. multiplying x^2 to both sides (since multiplying square values maintain the direction of the inequality sign), x>x^3? , x^3-x>0?, x(x-1)(x+1)>0? gives us -1<x<0 or 1<x?. Using both 1) and 2), the range of que doesn't include the range of con. Therefore E is the answer.
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
Is
/frac{x^n}{x^n+1} > /frac{x^n+1}{x^n}

1) x<0
2) n<0
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
Expert Reply
techiesam wrote:
Is
/frac{x^n}{x^n+1} > /frac{x^n+1}{x^n}

1) x<0
2) n<0


Merging topics. Please follow the rules when posting a question: https://gmatclub.com/forum/rules-for-po ... 33935.html Pay attention to rule 3.

Also, you might find Writing Mathematical Formulas on the Forum post helpful: https://gmatclub.com/forum/rules-for-po ... l#p1096628
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
Is x^n/x^(n+1) > x^(n+1)/x^n?

(1) x < 0

(2) n < 0

x^n/x^(n+1) > x^(n+1)/x^n ==> x^2n > x^2(n+1)
ie X^2 < 1 , therefor the range of X is(-1, 1)

So statement 1 & 2 are not enough to get the sollution
so Ans> E
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
tejal777 wrote:
Is \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)?

(1) x < 0

(2) n < 0


DS:
\(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)
\(\frac{1}{x}>\frac{x[}{fraction]\)

Statement 1 : x<0
-1<x<0, \([fraction]1/x}>\frac{x[}{fraction]\)
x = -1, \([fraction]1/x}=\frac{x[}{fraction]\)
x<-1, \([fraction]1/x}<[fraction]x[/fraction]\)
NOT SUFFICIENT

Statement 2: n<0 has no significance
NOT SUFFICIENT

Answer E
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
tejal777 wrote:
Is \(\frac{x^n}{x^{n+1}}>\frac{x^{n+1}}{x^n}\)?

(1) x < 0

(2) n < 0



First simplify the question stem: x^n/x^n+1 > x^n+1/x^n --> x^-1>x --> 1/x >x ----> is x negative or a fraction or a negative fraction?

(1) x<0

Let x=-1 1/-1 >-1 No
let x = -3 1/-3 >-3 Yes
NS

(2) n<0 Question does not depend on n, NS

(1) and (2) Since (1) NS and question does not depend on (2) NS OA is E
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Re: Is x^n/x^(n+1) > x^(n+1)/x^n? [#permalink]
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