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Proving $1^3+ 2^3 + \cdots + n^3 = \left (\frac {n (n+1)}...

Dec 9, 2014 · Hint $ $ First trivially inductively prove the Fundamental Theorem of Difference Calculus $$\rm\ F (n) = \sum_ {k\, =\, 1}^n f (k)\, \iff\, F (n) - F (n\!-\!1)\, =\, f (n),\ \ \, F (0) = 0\qquad$$ The re...

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Prove that $2^n3^ {2n}-1$ is always divisible by 17

7 Prove that $2^n3^ {2n} -1$ is always divisible by $17$. I am very new to proofs and i was considering using proof by induction but I am not sure how to. I know you have to start by verifying the statement is true fo...

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Mathematical induction: $9$ divides $n^3 + (n+1)^3 + (n+2)^3$

Apr 18, 2015 · First, show that this is true for n=0: 03+ (0+1)3+ (0+2)3=9 Second, assume that this is true for n: n3+ (n+1)3+ (n+2)3=9k Third, prove that this is true for n+1: (n+1)3+ (n+2)3+ (n+3)3= 9k−n3+ (n+3)3= T...