## ksaimouli 3 years ago integratebb

1. ksaimouli

3siny sqtcosy dy

2. ksaimouli

$\int\limits_{}^{}3\sin y \sqrt{cosy}$

3. anonymous

substitute u = cos(y), du = -sin(y) dy

4. ksaimouli

yup i did i am getting $-3\sqrt{cosy}$

5. anonymous

but cos(y) is u.

6. anonymous

$\int -3\sqrt{u} du$is a pretty easy integral.

7. ksaimouli

|dw:1357088383865:dw|

8. ksaimouli

see i am getting <-3 {sqrtcosy}/>

9. ksaimouli

$-3 {\sqrt cosy}$

10. anonymous

I reiterate that cos(y) is just u.

11. anonymous

so that is -3 sqrt(u)

12. ksaimouli

yes thats what i did -3 sqrt(u) and before we said u=cosx so i rewrote it back

13. ksaimouli

is that right answer for this question 3siny sqtcosy dy

14. anonymous

No. After your substitution the integral becomes $\int -3 \sqrt{u} du$ you need to integrate this, which you should be able to do in two seconds. Then, you can replace all the u's with cos(y)'s and then you'll be done.

15. MrDoe

jemurray3 is correct, just think of the square root as u^1/2 i think thats what your having trouble with

16. ksaimouli

-2u^(3/2)

17. ksaimouli

thx