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A proof by induction 2006-04-09
From Sharon:
prove by induction: For every n>1, show that
2 + 7 + 12 + ...+ (5n-3) = n(5n-1)/2

Answered by Penny Nom.
Proof by induction 2006-02-10
From Victoria:

how do i prove by induction on n that
n
Σ 1/i(i+1) = n/(n+1)
i=1

for all positive integers n


Answered by Penny Nom.
Proof by induction? 2005-08-10
From Peter:

I am a lecturer and am having a problem with the following Proof by
Induction.

If

(N x N x N x N) + (4 x N x N x N) + (3 x N x N) + (N) = -4000

Prove that N is even!


Answered by Chris Fisher and Penny Nom.
Proof by induction 2004-11-20
From Vic:
Problem: Find the first 4 terms and the nth term of the infinite sequence defined recursively as follows:

a(1) = 3 and a(k+1) = 2a(k) for k -> 1.

Note: Quantities in brackets are subscripts
-> means 'equal to or greater than'.

Using the recursive formula, the first 4 terms are; a(1) = 3, a(2) = 6, a(3) = 12, a(4) = 24

The nth term a(n) = 2n-1 x 3 (equation 1)

Equation 1 must be proven using mathematical induction. This is where I am having a problem.

Answered by Penny Nom.
n! > n^2 2004-03-30
From Jose:
How can you prove by mathematical induction that:

n! > n2.

Answered by Penny Nom.
Proof by induction 2004-03-02
From Chris:
I need some help of how to solve the problem

"use the principle of mathematical induction to prove that the following are true for all positive integers"

cos(n x pi + X) = (-1)^n cosX

any help would be appreciated

Answered by Penny Nom.
A functional equation 2002-10-14
From Rob:
Let f be a function whose domain is a set of all positive integers and whose range is a subset of the set of all positive integers with these conditions: a) f(n+1)>f(n)

b) f(f(n))=3(n)

Answered by Claude Tardif.
Proof by induction 2002-09-26
From Pooh:
Use induction to show that

1 2 + 2 2 + .....+n 2 = (n 3)/3 + (n 2)/2 + n/6

Answered by Paul Betts.
Proof by induction 2002-08-31
From Tabius:
Use mathematical induction to prove that the following formulae are true for all positive integers:

a) 1 + 3 + 5+...+(2n - 1) = n 2

b) 2 n > n.


Answered by Penny Nom.
Proof by induction 2002-02-20
From Tamaswati:
How do I prove the assertion that "the determinant of an upper triangular matrix is the product of the diagonal entries" by mathematical induction? (Before I check this assertion for a few values of n how do I rephrase the assertion slightly so that n appears explicitly in the assertion?)
Answered by Penny Nom.
Proof by induction 2001-10-16
From John:
Can you help me with any of these?
  1. For any natural number n > 1, prove that

    (4n) / (n + 1) < [(2n)!] / [(n!)2].

  2. For any natural number n > 1, prove that

    1/sqrt(1) + 1/sqrt(2) + 1/sqrt(3) + ... + 1/sqrt(n) > sqrt(n).

  3. For any natural number n and any x > 0, prove that

    xn + xn - 2 + xn - 4 + ... + x-n >= n + 1.

Answered by Penny Nom.
Proof by induction 2001-09-30
From Kyle:
I'm trying to learn induction and I need to see how this done please help with this problem...

20 + 21 + 22 +... + 2n = 2n+1 -1 is true whenever n is a positive integer.


Answered by Penny Nom.
Harmonic numbers 2001-05-23
From Leslie:
The harmonic numbers Hk, k = 1,2,3.....are defined by Hk = 1 + 1/2 + 1/3....1/k

I am trying to prove by mathematical induction:

H2n >= 1 + n/2 , whenever n is a nonnegative integer.

H8 = H23 >= 1 + 3/2

Can you help?


Answered by Harley Weston.
A sequence of even terms 2001-04-29
From A student:
A sequence c is defined recursively as follows:

c0 = 2
c1 = 4
c2 = 6

ck= 5ck-3 for all integers

Prove that cn is even for all integers.


Answered by Leeanne Boehm and Penny Nom.
Induction 2000-09-07
From Joe Peterson:
How do I prove by the principal of mathematical induction?
1.n+2.(n-1)+3.(n-2)+.....+(n-2).3+(n-1).2+n.1=(n(n+1)(n+2))/6

Answered by Paul Betts.
 
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