# Math Is Fun Forum

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## #1 Help Me ! » Damping Equation » 2020-01-12 12:29:14

Anthony Lahmann
Replies: 0

How do you solve the differential equation

?
As most of you know, this the damping equation where a is the strength of the spring, b is the linear part of the damping coefficient, and c is the quadratic part of the damping coefficient of the spring.

## #2 This is Cool » Half-Exponential Function » 2020-01-11 15:16:04

Anthony Lahmann
Replies: 1

Is there a function:

such that:
?

Here's how I did it:

which is wrong. What happened? (W is the Lambert W function)

## #3 This is Cool » Proof All Numbers are Equal » 2020-01-05 19:20:21

Anthony Lahmann
Replies: 6

Let's prove that all numbers are equal.

What went wrong?

## #4 Re: This is Cool » When is n(2n+1) a palindrome? » 2019-05-29 15:10:14

Jaspers wrote:
Anthony Lahmann wrote:

If

is a palindrome, when is
a palindrome? By looking at this chart, it looks like the only values that work are
. The values of
are
. Is it true that these are the only palindromes of the form
, where
is a palindrome? If true, prove why. Otherwise, find a counterexample.

Hi Anthony.

I’ve found another one:

Is that the next smallest one?

## #5 Re: This is Cool » When is n(2n+1) a palindrome? » 2019-05-29 15:08:35

phrontister wrote:

Hi Anthony & Jaspers;

I found these:

The statement "0 is a palindrome" is ambiguous. That's why I excluded it.

## #6 This is Cool » When is n(2n+1) a palindrome? » 2019-05-23 16:27:16

Anthony Lahmann
Replies: 6

If
is a palindrome, when is
a palindrome? By looking at this chart, it looks like the only values that work are
and
. The values of
are
and
. Is it true that these are the only palindromes of the form
, where
is a palindrome? If true, prove why. Otherwise, find a counterexample.

## #7 Re: This is Cool » Integral of 1/sqrt(1-x^2) » 2019-05-13 12:23:15

bob bundy wrote:

hi Anthony Lahmann

Welcome to the forum.

According to Wolfram Alpha, this is sin-1(x) and the second is -sin-1(x).  So there's a sign error in there somewhere.  I'll try to track it down later.

Bob

There is nothing wrong with this! I differentiated the u correctly, and I solved for x correctly.

## #8 This is Cool » Integral of 1/sqrt(1-x^2) » 2019-05-12 11:45:12

Anthony Lahmann
Replies: 5

How do you integrate

by u-substitution? Here's how I did it:

After we did the u-substitution, we end up with the exact same integral, but with a negative in the front. What happened?