What is the difference? I was pretty bored last night so I got onto Yahoo Answers and answered a few calculus questions. It was a simple integration by parts question:(adsbygoogle = window.adsbygoogle || []).push({});

[itex]\int[/itex]xsin(x) dx

I solved as:

u = x

du = dx

dv = sin(x) dx

v = -cos(x)

uv - [itex]\int[/itex]vdu

-xcos(x) + [itex]\int[/itex]cos(x)dx = sin(x) - xcos(x) + c

I later got a thumbs down by a second answerer, saying that solving using differentials is much more difficult to do, and that it's preferable to answer using derivatives.

I don't understand. I mean, I know how to solve using derivatives and functions instead of differentials, but how is it more difficult, and how is it the wrong approach? It just kept bugging me all night since I have always solved in this form and never thought it was wrong or difficult. There is no big difference solving with functions either:

[itex]\int[/itex] f'(x)g(x) dx = f(x)g(x) - [itex]\int[/itex]f(x)g'(x)dx

Only that you choose for a function and a derivative of a function. Am I missing something fundamental? Maybe I'm being too sensitive. I don't like getting thumbs down when I know I did something right. :( lol Any insight would be greatly appreciated. Thanks

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Solving integration by parts using derivatives vs differentials?

Loading...

Similar Threads - Solving integration parts | Date |
---|---|

I Solving an integral | Monday at 4:38 PM |

I Solving integral | Feb 9, 2018 |

I Understanding an integral | Jan 31, 2018 |

I Solving this integral equation | Nov 3, 2017 |

B How do I solve this integral? | Jun 22, 2017 |

**Physics Forums - The Fusion of Science and Community**