Inspired by tamirat solomon

what is the common value of n for which n belongs to natural numbers 29 7 n + 39 6 n = 49 5 n 297^n+396^n=495^n

4 3 1 2

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6 solutions

Akash Gupta
Jan 31, 2015

Lets apply all values one by one
See only the last digits.
7^1 +6^1 = 5^1(See only last digits)
13=5(See last digits)
3=5 false
Again, See only the last digits.
7^2 + 6^2 = 5^2
49 + 36 = 25
In that also see the last digit.
9+6=15 So, this can be true. Like this see all others also
7^3 + 6^3=5^3
3 + 6 = 5 (only the lasts digits) So, this is false
7^4 +6^4 = 5^4
1 + 6 = 5(last digits) false
Thus the only possible value of n is 2 . So the answer is 2

this cant be said as an solution

sudoku subbu - 6 years, 4 months ago

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Yeah, its not the solution but it is the logic which I used

Akash Gupta - 6 years, 4 months ago

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LOGISTICS CAN ONLY MME USED IN COMINATORICS NOT IN MATHEMATICS

sudoku subbu - 6 years, 4 months ago

Only squares of two integers can be equal to square of a third integer. Sum of any other power, n \neq 2, of two integers can never be equal to n.th power of any integer.

Tom Engelsman
Mar 7, 2021

We can write the above equation as:

29 7 n + 39 6 n = 49 5 n ( 3 3 1 1 1 ) n + ( 2 2 3 2 1 1 1 ) n = ( 3 2 5 1 1 1 1 ) n 3 n + 4 n = 5 n 297^n + 396^n = 495^n \Rightarrow (3^3 11^1)^n + ( 2^2 3^2 11^1)^n = (3^2 5^1 11^1)^n \Rightarrow 3^n + 4^n = 5^n

which is satisfied for n = 2 . \boxed{n=2}.

Just at sight remenbering Fermat Last Theorem, we must exclude exponent 3 and 4 then the only answer left is the sum of squares.

Jeff Bernard
Feb 14, 2015

If we divide all terms by the largest common divisor, 99 we get
295/99=3 396/99=4 495/99=5

A triangle with sides equal to 3, 4, and 5 will define a right triangle. The Pythagorean Theorem gives us a^2 + b^2 = c^2.

n=2

Ya Ya this is the perfect solution

sudoku subbu - 6 years, 3 months ago

If we divide all terms by the largest common divisor, 99 99 we get 295 99 = 3 , 396 99 = 4 , 495 99 = 5 \frac{295}{99}=3, \frac{396}{99}=4 , \frac{495}{99}=5

A triangle with sides equal to 3 , 4 , 3, 4, and 5 5 will define a right triangle.

The Pythagorean Theorem gives us a 2 + b 2 = c 2 a^{2} + b^{2} = c^{2} .

n = 2 n=2

Sir, I request you to copy the L a T e X LaTeX off my solution and repost your solution, it'll look better then ¨ \ddot\smile . I didn't mean to be rude, If you feel so, then I'm sorry .

A Former Brilliant Member - 6 years, 3 months ago
Vishal S
Feb 1, 2015

This just a simple question

If you know then answer the question dont misuse the solutions of others!

sudoku subbu - 6 years, 3 months ago

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