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What is the smallest integer n for which 25^n > 5^12 ?

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What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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What is the smallest integer n for which 25^n > 5^12 ?

(A) 6
(B) 7
(C) 8
(D) 9
(E) 10
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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 06 Apr 2013, 23:48
When i worked this problem I did the following:

5^12 -> 5*5^11 but why is 5*5^11 not equal 25^11?

I am stuck on this part, and im sure it is simply to do with order of operations but i cant wrap my mind around it.

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 07 Apr 2013, 01:06
specialxknc wrote:
When i worked this problem I did the following:

5^12 -> 5*5^11 but why is 5*5^11 not equal 25^11?

I am stuck on this part, and im sure it is simply to do with order of operations but i cant wrap my mind around it.


5*5^11 = 5^1 * 5^11 = 5*(1+11)

25^11 = (5^2)^11 = 5^(2*11) = 5^22

Rules for exponents are as follows:

(1) \(x^m * x^n = x^(m+n)\)
(2) \(x^m / x^n = x^(m-n)\)
(3) \(x^(-m)\) = \(1/x^m\)
(4) \(x^0\) =1
(5) \((x^m)^n\) = \(x^(mn)\)
(6) \(x^m * y^m\) = \((xy)^m\)

Last edited by doe007 on 10 Apr 2013, 23:20, edited 4 times in total.

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 07 Apr 2013, 07:25
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specialxknc wrote:
When i worked this problem I did the following:

5^12 -> 5*5^11 but why is 5*5^11 not equal 25^11?

I am stuck on this part, and im sure it is simply to do with order of operations but i cant wrap my mind around it.


Because you dropped parenthesis. 5*5^11 is ambiguous, so on one hand it could equal (5*5)^11, which is 25^11. But on the other hand it might mean 5*(5^11), which is 5^12.

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Misterholmes

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 27 Feb 2014, 01:47
5^12 can be written as 25^6
When n=6, the equation becomes equal, so 7 should be the answer

Answer = B
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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 11 Sep 2014, 10:53
Walkabout wrote:
What is the smallest integer n for which 25^n > 5^12 ?

(A) 6
(B) 7
(C) 8
(D) 9
(E) 10



25^n > 5^12

5^2n>5^12

2n>12

n has to be minimum 7

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 09 Jun 2016, 14:10
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Walkabout wrote:
What is the smallest integer n for which 25^n > 5^12 ?

(A) 6
(B) 7
(C) 8
(D) 9
(E) 10


To solve, we want to get the bases the same. Thus we need to break 25^n into prime factors.

25^n = (5^2)^n = 5^(2n) (Remember that when we have a power to a power, we multiply the exponents.)

We can use the new value in the given inequality:

5^(2n)> 5^12

Since we have the same bases on either side of the inequality we can drop the bases and set up an equation involving just the exponents.

2n > 12

n > 6

Because n is greater than 6, the smallest integer that satisfies the inequality 25^n > 5^12 is 7.

The answer is B.
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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 09 Jun 2016, 22:46
Walkabout wrote:
What is the smallest integer n for which 25^n > 5^12 ?

(A) 6
(B) 7
(C) 8
(D) 9
(E) 10


\(25^n\) > \(5^12\)
\(5^2n\) > \(5^12\)

Since 5 is a positive number

2n> 12

n > 6

Smallest integer value for which n> 6: 7.

B is the answer

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Re: What is the smallest integer n for which 25^n > 5^12 ? [#permalink]

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New post 25 Mar 2017, 06:19
be careful here, we are not looking for an answer that would give us >=0, but >=
5^2n>5^12
n is 7

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Re: What is the smallest integer n for which 25^n > 5^12 ?   [#permalink] 25 Mar 2017, 06:19
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What is the smallest integer n for which 25^n > 5^12 ?

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