Thread: Integration

Alright so I'm a little confused with basic integration.


But what if theres a constant infront of dx.
For example


What changes then?

As 7 is a constant, it is not affected by the integration, so you can do this:








or if you like to think of it this way:

Originally Posted by Gusbob

As 7 is a constant, it is not affected by the integration, so you can do this:








or if you like to think of it this way:

Thanks, another quick question,

Or do I have to multiply it by the derivative of 4x+2?

You multiply by the derivative, but don't forget to divide it.

For this one, I'll take the 7 out again and use the substitution u = 4x + 2. du = 4 dx.

You need a 4 on top, so multiply by .



Since 1/4 is a constant, I took it out like I did with the 7. (Note: only constants that are multiplied or divided can be taken out, addition or subtraction of constants are integrated.)

(since du = 4dx; u = 4x+2)

=

Originally Posted by Gusbob

You multiply by the derivative, but don't forget to divide it.

For this one, I'll take the 7 out again and use the substitution u = 4x + 2. du = 4 dx.

You need a 4 on top, so multiply by .



Since 1/4 is a constant, I took it out like I did with the 7.

(since du = 4dx; u = 4x+2)

=

Thanks a ton, things are a lot clearer now!

but. = using the same technique by isolating the derivative of the quantity