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Raithed
China7078 Posts
This is my takehome test that is due tomorrow. Unfortunately, I do not know how to do any of these... Explanations on how to integrals would be greatly appreciated. I am working on these on my own, and would like ideas, or someone to talk to on AIM or something to discuss how to do these. ![[image loading]](http://img134.imageshack.us/img134/2503/img001zq3.jpg)  | ||
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fight_or_flight
United States3988 Posts
![[image loading]](http://img233.imageshack.us/img233/3386/reviewzu8.png) | ||
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fight_or_flight
United States3988 Posts
![[image loading]](http://img138.imageshack.us/img138/483/review2fr3.png) | ||
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Raithed
China7078 Posts
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fight_or_flight
United States3988 Posts
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doob10163
6 Posts
I have 1, 2, 3, 4, 6, 10, and 14 done Not quite sure how to go about the rest of these. Any ideas? | ||
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fight_or_flight
United States3988 Posts
cos^3 = cos cos^2 = cos (1 - sin^2) then u = sin, du = 1/cos dx. For the rational ones do partial fractions. edit: also, you can use http://integrals.wolfram.com/index.jsp to check your work | ||
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doob10163
6 Posts
i did 4 times the integral (sec^2 x) ^2 which then became sex^2 x (tan ^2x + 1) is this the right approach to be taking? If so , what is the proper next step? | ||
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paper
13196 Posts
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Saracen
United States5139 Posts
for 9. "which became sex^2x" ahah i see what you did there ^_^ sec^2(x)tan^2(x) function to a power times its derivative and S sec^2(x) dx = tanx well at least i'm pretty sure how it is i forgot all this shitty trig identity integration stuff | ||
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fight_or_flight
United States3988 Posts
then its the integral of u^2 + 1 = 1/3 u^3 + u or 1/3 (tanx)^3 + tanx giving 4/3 (tanx)^3 + 4tanx | ||
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Saracen
United States5139 Posts
right?  | ||
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doob10163
6 Posts
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fight_or_flight
United States3988 Posts
Basically I've just been working off my own flowchart to be honest. | ||
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doob10163
6 Posts
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doob10163
6 Posts
The second integral of #3 being what happens after you split the fraction and are left with 18x over the denominator | ||
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fight_or_flight
United States3988 Posts
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Saracen
United States5139 Posts
On April 02 2008 12:55 doob10163 wrote: Any ideas on how to do the 2nd integral of 3, 5, 11, 12, 13, 15, 16, 17, 18, and 19? The second integral of #3 being what happens after you split the fraction and are left with 18x over the denominator separate it into 2 fractions 1/(1+3x^2) and -6x/(1+3x^2) after you take out the 3 1st one is arctan 2nd one is function to a power times its derivative | ||
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Saracen
United States5139 Posts
u-sub u=lnx du=dx/x x=e^u then use parts (tabular method) | ||
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Saracen
United States5139 Posts
it's really straightforward...idk why it's hard? sec(theta) = sqrt(4y^2+1), dy=(sec^2(theta))d(theta)/2 | ||
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