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Algebra Level 2

What is the 1 4 th 14^\text{th} root of 14 14 14 ? {14}^{{14}^{14}}?

14 14 {14}^{14} 14 14 8 {14}^{{14}^{8}} 14 14 13 {14}^{{14}^{13}} Cannot be solved

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5 solutions

Mj Santos
Feb 2, 2015

Note that:

14 14 14 × 1 14 = 14 14 14 × 14 1 = 14 14 13 {14}^{{14}^{14} \times \frac{1}{14}}={14}^{{14}^{14} \times {14}^{-1}}=\boxed{{14}^{{14}^{13}}}

You should also submit this (another entry) to the Valentine's Day Themed contest .

It's tangentially related with the number 14, but a very nice question!

Calvin Lin Staff - 6 years, 4 months ago

I've seen a similar problem before, so this was easy. But this is a nice problem!

Satvik Golechha - 6 years, 4 months ago

Level 3 ! This is such a simple question. May be many people marked 3rd option :)

Nihar Mahajan - 6 years, 4 months ago

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Right, most people chose 1 4 14 14 ^ {14} .

Calvin Lin Staff - 6 years, 4 months ago

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More than 50% of the people chose 1 4 14 14^{14}

MJ Santos - 6 years, 4 months ago

I just did right now. I chose option 3 :) , good to know i am not the only one.

Hana Wehbi - 5 years, 1 month ago

Its wrong HV u checked it properly

Rohit Singh - 6 years, 4 months ago

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@Rohit Singh Why do you think it is wrong? What would your answer be?

Note that a b c ( a b ) c a^ {b ^ c } \neq \left( a ^ b \right) ^ c .
Instead, a b c = a ( b c ) a^ { b^ c} = a ^ { \left( b^ c \right) } .

Please review Rules of exponents - Power

Calvin Lin Staff - 6 years, 4 months ago

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@Calvin Lin This is the best way to remove the miss understanding. Thanks. I too had fallen into the trap!!

Niranjan Khanderia - 6 years, 4 months ago

@Calvin Lin You are right, in view of the Tower Rule, but what if want to use the second one? I mean, when you write a^b^c without any parenthesis how would people take it? Aren't there two possible ways to think of a^b^c? So, in my view, brackets should be introduced and hence two choices (2nd and 4th) must be acceptable. Try http://www.wolframalpha.com/input/?i=%2814%5E14%5E14%29%5E%281%2F14%29

Waseem Jafary - 5 years, 6 months ago

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@Waseem Jafary See the Rules of Exponents

Without parenthesis, a^b^c is read from right to left, giving us a ( b c ) a ^ { \left( b^c \right) } . If you want ( a b ) c \left( a^b \right) ^ c , then you have to state it clearly. One reason why people don't do it, is because it is equivalent to a b c a ^ { bc } . So, unless you are a testing understanding, there isn't a strong reason to do so.

Calvin Lin Staff - 5 years, 6 months ago

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@Calvin Lin I agree. Thank you...

Waseem Jafary - 5 years, 6 months ago

@Calvin Lin Thanks Calvin Lin I had a strong misconception about exponents!

Bhavesh Ahuja - 6 years, 4 months ago

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@Bhavesh Ahuja had is the important word here. Glad you fixed it.

Now ask your friends and see how many of them got it right!

Calvin Lin Staff - 6 years, 4 months ago

@Calvin Lin Yeah I fell into that trap.

Sam Maltia - 5 years, 8 months ago

Then Why when you use another example like 2^2^2 doesn't work. I see that 2^2 2 is not equal to squareroot of 2^2 2/2 = 2*2=4 when the answer to the question is 16

Pedro Valdericeda - 6 years, 4 months ago

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This does work. 2^2^2=2^4=16. The square root of this is 4. The above method yields sqrt(2^2^2)=2^2^1=2^2=4. From what I can tell, you have your example written backwards.

Kunal Kantaria - 5 years, 12 months ago

When base are same then this rule applies: A^b * A^c= A^(b+c)

How is 14^14^13 correct ? Won't correct be 14^14??

Tanvi Rastogi - 5 years ago

ohhhhhhhhh

Rabiul Awal - 5 years ago

Why is eveeryone so smart

Erkan Yagmurov - 4 years, 3 months ago

What thin is this?, (x^x^x)^(1/x) should to be x^x.

Angel Raygoza - 1 year, 4 months ago

Nice solution

manikanta komarla - 6 years, 4 months ago

Wrong I don't believe in this proof what u doing justify it with. √ a^b

Rohit Singh - 6 years, 4 months ago

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The power rule of exponents states: a b c a^{b^{c}} = a ( b c ) a^{(b^{c})}

So: 1 4 1 4 14 14^{14^{14}}

Is the same as: 1 4 ( 1 4 14 ) 14^{(14^{14})}

Which is the same as: 1 4 ( 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 ) 14^{(14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14)}

Therefore when you have: 1 4 1 4 14 14 \sqrt[14]{14^{14^{14}}}

It is the same as: 1 4 ( 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 ) 14 \sqrt[14]{14^{(14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14)}}

So according to the fraction rule of exponents: a n m \sqrt[m]{a^{n}} = a n / m a^{n/m}

That means: 1 4 1 4 14 14 \sqrt[14]{14^{14^{14}}}

Is the same as: 1 4 ( 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 14 ) 14^{(\frac {14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14}{14})}

Which works out to be: 1 4 ( 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 ) 14^{(14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14 \times 14)}

Then simplifies to be: 1 4 1 4 13 14^{14^{13}}

matt mcc - 6 years, 4 months ago

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you explained it beautifully,thanks.

manish kumar singh - 5 years, 7 months ago

OK, now it's clear. Thank you!

Artem Soltomuradov - 5 years, 1 month ago

Dude this is a beautiful explanation.

J kay - 4 years, 4 months ago

This really helpful

Venkat Shiva V - 5 years ago

Dude I think this is wrong. Are you sure this is right? Cause you are wrong

victor benevides - 6 years, 4 months ago

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Why do you think it is wrong? What would your answer be?

Note that a b c ( a b ) c a^ {b ^ c } \neq \left( a ^ b \right) ^ c .
Instead, a b c = a ( b c ) a^ { b^ c} = a ^ { \left( b^ c \right) } .

Please review Rules of exponents - Power

Calvin Lin Staff - 6 years, 4 months ago

Are u zuando?cuz it looks like you are

Mr Yovan - 5 years, 9 months ago
Paola Ramírez
Feb 6, 2015

One property of roots is that m n = m 1 n \sqrt[n]{m}=m^{\frac{1}{n}}

So 1 4 1 4 14 14 = ( 1 4 1 4 14 ) 1 14 = 1 4 1 4 13 \sqrt[14]{14^{14^{14}}}=({14^{14^{14}}})^{\frac{1}{14}}=\boxed{{14^{14^{13}}}}

No way. Check your math please

nice guy - 4 years, 10 months ago

So (2^3)^3= 2^9 so 14 times 1/14=1 so the second 14 exponent cancels

Jared Beaufait - 4 years, 4 months ago

From the property of exponents : If k = m × n k = m \times n , then ( a m ) n = a k (a^{m})^{n} = a^{k} .

In this case of this problem : let the variables a = 14 , k = 1 4 14 , m = 1 4 13 \ \ \ a = 14 \ \ \ , \ \ \ k = 14^{14} \ \ \ , \ \ \ m = 14^{13} \ \ then n = 1 4 1 \ \ \ n = 14^{1} . a k = 1 4 1 4 14 = ( a m ) n = ( 1 4 1 4 13 ) 14 \therefore \ \ a^{k} = 14^{14^{14}} = (a^{m})^{n} = (14^{14^{13}})^{14} 1 4 1 4 14 14 = ( 1 4 1 4 13 ) 14 14 = 1 4 1 4 13 \therefore \ \ \sqrt[14]{14^{14^{14}}} = \sqrt[14]{(14^{14^{13}})^{14}} = \boxed{14^{14^{13}}}

This explanation is perhaps the most elegant of any so far. It doesn't require one to remember the "tower rule", nor that this problem is read right to left. @matt mcc has a clear solution above as well, but it takes more keystrokes!

William Burdick - 4 years, 10 months ago

Problem: What is the 14th root of 14 14 14 {14}^{{14}^{14}} ?

Solution: We wish to solve this expression. To make this easier to understand, we could let x = 14 14 x={14}^{14} . Then, the expression can be written as 14 x 14 \sqrt[14]{{14}^{x}} . Next, recall that a radical can be expressed as a fractional exponent. So, our expression can be written as ( 14 x ) 1 14 ({{14}^{x}})^{\frac{1}{14}} . Using the power rule, we can see that it simplifies to 14 x 14 {14}^{\frac{x}{14}} . Substituting the value of x x into the equation and simplifying it, we get the answer 14 14 13 {14}^{{14}^{13}} . \square

👍 nice way to solve this problem

Sushma Patle - 4 years, 4 months ago

U are genius

Fgh Fggccfcv - 4 years, 3 months ago
Stephen Safee
Sep 28, 2016

1 4 14 = 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 14^{14}=14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14

1 4 ( 1 4 14 ) = 1 4 ( 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 ) 14^{(14^{14})}=14^{(14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14)}


The 14th root of 1 4 ( 1 4 14 ) = ( 1 4 ( 1 4 14 ) ) 1 / 14 = 1 4 ( 1 4 14 ) 1 / 14 14^{(14^{14})}=(14^{(14^{14})})^{1/14}=14^{(14^{14})1/14}

= 1 4 ( 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 ) / 14 =14^{(14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14)/14}

= 1 4 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 14 =14^{14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times\frac{14}{14}}

= 1 4 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 14 × 1 =14^{14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times14\times1}

= 1 4 1 4 13 =\boxed{14^{14^{13}}}

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