**News Alert:**Experts Exchange Confirmed as Safe in Cloudbleed Leak Read More

Solved

Posted on 2014-04-24

I reading the solution of a dif eq

Y'' -m^2 *n^2 * y =

Y = c1e1 ^ ( -mny) + c2e2 ^ ( + mny )

how did he get this result ?

and X'' + n^2X

then X = c3 sin nx + c4 cosnx

Y'' -m^2 *n^2 * y =

Y = c1e1 ^ ( -mny) + c2e2 ^ ( + mny )

how did he get this result ?

and X'' + n^2X

then X = c3 sin nx + c4 cosnx

4 Comments

I still might not be able to help, but the text form of complex math is an additional and unpleasant hurdle.

A*b*b*exp(bt) + n²*A*exp(bt) = 0

and this can only be so if b²=-n² and this only if b = i*n where i is the square root of -1.

(Because e to the power of anyting is NEVER zero, and A=0 is a tribial solution)

And n can be positive of negative, since it square is aloways positive, so the exponentials are exp(int) and exp(-int), and it you remember your trig, this is sin(nt) and cos(nt) and hence the result.

So back into the first equation where n² is m²*n² and presto the result.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Title | # Comments | Views | Activity |
---|---|---|---|

how to find inverse of a nxn matrix when n is large ie n=8,10... | 9 | 43 | |

How to onstruct a table | 4 | 49 | |

Standard Deviation | 2 | 36 | |

Interest rate formula | 7 | 66 |

Join the community of 500,000 technology professionals and ask your questions.