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Shades of Fermat's Last Theorem

The familiar Pythagorean 3-4-5 triple gives one solution to (x-1)^n + x^n = (x+1)^n so what about other solutions for x an integer and n= 2, 3, 4 or 5?


Find the positive integer solutions of the equation (1+1/a)(1+1/b)(1+1/c) = 2

Code to Zero

Find all 3 digit numbers such that by adding the first digit, the square of the second and the cube of the third you get the original number, for example 1 + 3^2 + 5^3 = 135.

Discrete Trends

Age 16 to 18
Challenge Level

As $n$ is an integer try finding $n^{1\over n}$ for some small values of $n$. What do you find? If you think you might have found the maximum value then you'll need to use the first part of the question to prove it really is the maximum. As the problem is about discrete (whole number) values you can find a solution without calculus. To show that

$$n^{1/n} < 1 + \sqrt {{2\over {n-1}}}$$

write $n^{1/n} = 1 + \delta$ and use the Binomial Theorem. If $n> 1$ then $\delta> 0$. Throw away all but one term of the Binomial expansion to get the inequality.