Question

Could someone double check my answer ? :) (Integration)

Answer 1

correct!
good work :)

Answer 2

woohoo! Thank you @hartnn :) Were on integration by parts its tricky O_o

Answer 3

cool!
welcome ^_^
once you have practiced few problems on by parts, you'll be able to do it mentally ;)

Answer 4

oo i hope so! I like math but when i don't understand something, I really don't know whats going on with everything else :|

Answer 5

we're here to clear any of your doubts :)

Answer 6

aw thank you. I might need your help checking another problem :/

Answer 7

sure

Answer 8

I got this marked wrong..

Answer 9

know cos 3x formula ?

Answer 10

well what i did what split in so that cos^2(5at)=1-sin^2(5at)

Answer 11

so my integral read: [1-sin^2(5at)]cos(5at)

Answer 12

then u put u= sin 5at ?

Answer 13

yes correct

Answer 14

integral (1/5a) (1-u^2) du

(1/5a) ( u - u^3/3) + c
(1/5a) (sin 5at - sin^3 5at /3 )

= sin 5at /5a - sin^3 5at/ 15a

i guess you just missed the "a"

Answer 15

du = 5a cos 5at dt

cos 5at dt = du/(5a)

Answer 16

i dont understand why the "a" would be there? :/

Answer 17

u = sin 5at
du = ... ?

Answer 18

5cos(5at) ?

Answer 19

no!

the "5a" is the constant

so, du = (5a) cos (5at)

Answer 20

du = 5a cos 5at dt

Answer 21

aww man! ok i see that. gosh these variables -_-

Answer 22

so would my answer be the same but with the "a" in the denominator?

Answer 23

yes, in both denominators

= sin 5at /5a - sin^3 5at/ 15a

Answer 24

ok lets see if this works *fingers crossed*

Answer 25

IT DID -_- haha omg

Answer 26

congrats! ;)

Answer 27

your the best :) thank you so much

Answer 28

not actually, but welcome ^_^
your smile is too good! :)

Answer 29

:) thank you