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  1. Prove that $1^3 + 2^3 + ... + n^3 = (1+ 2 + ... + n)^2$

    HINT: You want that last expression to turn out to be $\big (1+2+\ldots+k+ (k+1)\big)^2$, so you want $ (k+1)^3$ to be equal to the difference $$\big (1+2+\ldots+k+ (k+1)\big)^2- (1+2+\ldots+k)^2\;.$$ …

  2. $\\sum_{m=1}^{\\infty}\\sum_{n=1}^{\\infty} \\frac{m²n}{n3^m +m3^n}$

    Sep 8, 2020 · $\sum_ {m=1}^ {\infty}\sum_ {n=1}^ {\infty} \frac {m²n} {n3^m +m3^n}$. I replaced m by n,n by m and sum both which gives term $\frac {mn (m+n)} {n3^m +m3^n}$.how to do further?

  3. Proving by induction that $1^3 + 2^3 + 3^3 + \ldots + n^3 = \left ...

    Mar 25, 2013 · Need guidance on this proof by mathematical induction. I am new to this type of math and don't know how exactly to get started. $$ 1^3 + 2^3 + 3^3 + \ldots + n^3 = \left [\frac {n (n+1)} {2}\

  4. 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 …

  5. Find the z-transform of $n^2 3^n$ - Mathematics Stack Exchange

    Feb 28, 2022 · Start asking to get answers Find the answer to your question by asking. Ask question

  6. 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= …

  7. For how many positive values of $n$ are both $\frac n3$ and $3n$ four ...

    Oct 29, 2017 · 112 values is the number of positive values whose n/3 and n*3 both are 4-digit numbers.

  8. combinatorics - Prove that the sum over triples of non-negative ...

    Sep 15, 2020 · Problem Statement: Prove that for any positive integer $n$, $$\sum_ {n_1+n_2+n_3 = n} (-1)^ {n_1} = 1$$ where the summation is over all triples $ (n1, n2, n3)$ of non-negative integers with …

  9. Determining if H is a subgroup of G - Mathematics Stack Exchange

    Jan 26, 2019 · If I understand correctly, any a looks like $$a = 2^n3^n$$ So we could also say any b looks like $$b = 2^u3^v, u, v \in \mathbb {Z}$$ Then $$ab = 2^n3^m2^u3^v$$ $$ab= 2^ {n+u}3^ …

  10. Solve by induction: $n!> (n/e)^n$ - Mathematics Stack Exchange

    Aug 21, 2011 · To Prove : $n! > (n/e)^n$ The question seems easy but it ain't; anyone up for it ?