Help with integration!

**Tutu** · September 22nd 2013, 09:48 AM

Hi

I really need help with these two questions, for the first attachement I have no idea how to do that last part circled in pink

For the second attachement(labeled part e.)), I could not get the answer - I got $\frac{4sqrt{2}}{sqrt{3}}arctan(\frac{sqrt{2}}{sqrt {3}}) + c$ but the answer is $\2\frac{sqrt{2}}{sqrt{3}}arctan(\frac{sqrt{2}}{sqr t{3}}) + c$

Thank you so much in advance!

**FelixFelicis28** · September 22nd 2013, 10:29 AM

Originally Posted by Tutu

Hi

I really need help with these two questions, for the first attachement I have no idea how to do that last part circled in pink

For the second attachement(labeled part e.)), I could not get the answer - I got $\frac{4sqrt{2}}{sqrt{3}}arctan(\frac{sqrt{2}}{sqrt {3}}) + c$ but the answer is $\2\frac{sqrt{2}}{sqrt{3}}arctan(\frac{sqrt{2}}{sqr t{3}}) + c$

Thank you so much in advance!

1) You have $\int_0^3 f(x) \ dx = 8 = \int_c^d f(x-2) \ dx$

Integration by substitution - the substitution should be pretty easy to spot, bearing in mind the argument of $f(x-2)$ .

2) Their answer is correct, I cannot point out what you've done incorrectly unless you post your working OP, likely a small arithmetical error somewhere.

**Tutu** · September 22nd 2013, 07:58 PM

Hi thank you so much!

For the second, attached is my working, I had simply used the formula so its sort of one step..can you help me see where I went wrong?

**FelixFelicis28** · September 22nd 2013, 08:10 PM

Originally Posted by Tutu

Hi thank you so much!

For the second, attached is my working, I had simply used the formula so its sort of one step..can you help me see where I went wrong?

You haven't done $\int \frac{dx}{a^2 + (px+q)^2} = \frac{1}{ap} \arctan \left(\frac{px+q}{a}\right) + \mathcal{C}$

but rather:

$\int \frac{dx}{a^2 + (px+q)^2} = \frac{1}{a} \arctan \left(\frac{px+q}{a}\right) + \mathcal{C}$ .

**ibdutt** · September 22nd 2013, 08:54 PM

Thread: Help with integration!

LinkBack

Thread Tools

Display

Help with integration!

Re: Help with integration!

Re: Help with integration!

Re: Help with integration!

Re: Help with integration!

Similar Math Help Forum Discussions

Integration help please these are three small even basic integration problems

sketch the region of integration and change the order of integration.

Definite Integration - Double integration by parts

Simple Integration problem: Trigonometric Integration

Tricky integration, possibly Integration Factor

Search Tags