[Tulian]

Was hoping someone could help on this please, integrating with limits 1 to 9


I pulled out the 36 from the numerator , and made it:




After subbing in the limits I get the answer wrong as the answer given involves 12 pi ?

I got 36Pi ln25 , answer is 12Pi ln25 , I thought my method would usually work for these.

[RajPopat94]

When you're integrating lnf(x), what's the rule?

[Anonymous1994]

The format has to be f'(x)/f(x). So you have to take out 12, as then you're left with 3 at the top (the bottom differentiates to 3). You should be fine from there on out.

[Musical-Ocean]

notice you need a third of it

[Tulian]

(Original post by RajPopat94)
When you're integrating lnf(x), what's the rule?

If it's 1/something, then ln(something) right ? , but I took out the 36 as a constant so that shouldn't matter ?

[raheem94]

(Original post by Tulian)
If it's 1/something, then ln(something) right ? , but I took out the 36 as a constant so that shouldn't matter ?

[Tulian]

I totally forgot about the 1/a part after taking the 36 out.

Thanks everyone