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**dukebdx12****Member**- Registered: 2007-03-21
- Posts: 9

Calculus 2 help?

Need help with these questions. I have a test tomorrow and need help on knowing how to work these.....S stands for integration. And just help on any of these would be fine. Thanks

1) S 2/(x-9)^2 dx .... i got the answer -2/(x-9) but how did they get that because as far as I got is 2S1/(u^2) dx

2) S [x + 1/(3x-1)^3] dx

3) S (x^2-3)/(-x^3+9x+1) dx ......long division?

4) cotx ln(sinx) dx ........ havn't tried to work it yet.

5) S 2/((2x-1)^2+4) dx ...here you use arctan formula which is du/a^2+u^2 = 1/a arctan(u/a)+c and I have kinda got a and u figured out just need help putting in because this is diff. from what we did in class.

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**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

(1)

In general,

(2)Try putting the integrand into partial fractions.

(3)

(4)

Notice that

(5)

Try the substitution

*Last edited by JaneFairfax (2007-03-21 14:03:10)*

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**Stanley_Marsh****Member**- Registered: 2006-12-13
- Posts: 345

Can I use

in 2??Numbers are the essence of the Universe

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**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Or just

. Thatll work.Offline

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