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If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n=

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harish1986
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If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   Updated on: 17 Jan 2016, 11:25
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If n is an integer and \((−3)^{4n}=3^{7n−3}\) then n=

A. 1
B. 2
C. 3
D. 4
E. 5
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A

Originally posted by harish1986 on 17 Jan 2016, 11:07.
Last edited by Bunuel on 17 Jan 2016, 11:25, edited 1 time in total.
Renamed the topic and edited the question.
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   17 Jan 2016, 11:46
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harish1986 wrote:
If n is an integer and \((−3)^{4n}=3^{7n−3}\) then n=

A. 1
B. 2
C. 3
D. 4
E. 5


\((−3)^{4n}=3^{7n−3}\)

\(3^{4n}=3^{7n−3}\)

\(4n=7n−3\)

\(n=1\).

Answer: A.
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   02 Jul 2016, 09:57
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Hi, not clear why is the negative sign removed (−3)^4n, could you explain please....
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   02 Jul 2016, 10:23
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sony1000 wrote:
Hi, not clear why is the negative sign removed (−3)^4n, could you explain please....


Since n is an integer then 4n is even thus (−3)^(4n) = 3^(4n).
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   03 Jul 2016, 11:21
Right on.. Thank you.
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   19 Sep 2021, 12:36
Hi, But the stem doesnt say if 'n' is a positive or a negative integer. Then how could we conclude that (-3)^4n = 3^4n ??
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BrentGMATPrepNow
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   19 Sep 2021, 12:46
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bedarkaryashas wrote:
Hi, But the stem doesnt say if 'n' is a positive or a negative integer. Then how could we conclude that (-3)^4n = 3^4n ??


If a negative number is raised to an EVEN power, the result will always be positive.
For example, (-1)^4 = 1

Now notice that we can rewrite \((-3)^{4n}\) as \(((-3)^4)^n\)

So we get: \((-3)^{4n}=((-3)^4)^n=81^n=(3^4)^n\)

Does that help?
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   19 Sep 2021, 12:59
Hi Brent. Thank you for helping out. But my doubt is: the question steam doesn't state if n is +ve or -ve integer.
Accordingly, if n is a negative integer (assume n= -1) then the equation would be:
(-3)^(4* -1)
i.e. (-3)^ (-4)
i.e. (1/ 81)

What do you think?
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Re: If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   19 Sep 2021, 13:01
BrentGMATPrepNow wrote:
bedarkaryashas wrote:
Hi, But the stem doesnt say if 'n' is a positive or a negative integer. Then how could we conclude that (-3)^4n = 3^4n ??


If a negative number is raised to an EVEN power, the result will always be positive.
For example, (-1)^4 = 1

Now notice that we can rewrite \((-3)^{4n}\) as \(((-3)^4)^n\)

So we get: \((-3)^{4n}=((-3)^4)^n=81^n=(3^4)^n\)

Does that help?


Hi Brent. Thank you for helping out. But my doubt is: the question steam doesn't state if n is +ve or -ve integer.
Accordingly, if n is a negative integer (assume n= -1) then the equation would be:
(-3)^(4* -1)
i.e. (-3)^ (-4)
i.e. (1/ 81)

What do you think?
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BrentGMATPrepNow
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If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink] New post   19 Sep 2021, 13:07
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bedarkaryashas wrote:
BrentGMATPrepNow wrote:
bedarkaryashas wrote:
Hi, But the stem doesnt say if 'n' is a positive or a negative integer. Then how could we conclude that (-3)^4n = 3^4n ??


If a negative number is raised to an EVEN power, the result will always be positive.
For example, (-1)^4 = 1

Now notice that we can rewrite \((-3)^{4n}\) as \(((-3)^4)^n\)

So we get: \((-3)^{4n}=((-3)^4)^n=81^n=(3^4)^n\)

Does that help?


Hi Brent. Thank you for helping out. But my doubt is: the question steam doesn't state if n is +ve or -ve integer.
Accordingly, if n is a negative integer (assume n= -1) then the equation would be:
(-3)^(4* -1)
i.e. (-3)^ (-4)
i.e. (1/ 81)

What do you think?


But n = -1 is NOT a solution to the given equation, so that has no bearing on the question.

The value of n is implied by the equation \((−3)^{4n}=3^{7n−3}\)

When we solve the equation for n we get n = 1.

In other words, n cannot equal any other value (negative or positive) other than 1.
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If n is an integer and (−3)^{4n}=3^{7n−3}[/m] then n= [#permalink]
19 Sep 2021, 13:07
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