A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
Use a substitution to find....
anonymous
 one year ago
Use a substitution to find....

This Question is Closed

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0dw:1437224954877:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So i choose u=cos4t Derrivative gives du/dt=−4sin4t Then Rewrite sin4t dt=du/4 and finally i got to this 1/4∫sin^2 u du

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1I think it's one of those trigonometric .... where if the exponent is even and the exponent is odd...I forgot, but it does take long

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1ah trigonometric integrals

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1bu the problem is.. we have an exponent that's even (the sine_ and the exponent that's odd (cosine) and I can't find a good source at the moment that explains the rules for it nugh.

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1I think there are 3 cases one with all even exponents one with all odd exponents one with even and odd. and I hated these. I think I missed lecture eons ago

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0The answer in the book is (Sin^3 * 4t)/ 4 + constant

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1@peachpi it's getting late on my end.. can't think x.x

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I was thinking the trig substitution as well but it looks like you can use straight usub. u = sin (4t) du = 4 cos (4t) dt ¼ du = cos (4t) dt \[\frac{ 1 }{ 4 }\int\limits_{}u^2 du\]

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1yeah that's what came to my mind first but then I saw the format of the question and I was like does that trig integral stuff come into play?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0whered u get sin(4t) from?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0that's in the original integral. sin² 4t = (sin 4t)²

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1dw:1437225705494:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ohh i didnt know u could break it down like that. Alright let my try this again then.

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1yeah you can rewrite that sine like that I find it annoying when books have it in that notation so I change it

UsukiDoll
 one year ago
Best ResponseYou've already chosen the best response.1then I can see the u sub clearly...

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0alright let me see if i can solve this.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yup I got the correct answer as the book now. I didnt understand u could change it like that. THanks guys!
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.