Question

Quick question what is the antiderivative of 3sinxcosx?

Answer 1

wouldn't my u be sinx and du cosx?

Answer 2

Anti derivative .. hmn wait

Answer 3

Can we say ; antiderivative as "integration" also?

Answer 4

@mathslover yes we can

Answer 5

@.Sam. Please let me try?

Answer 6

I just need to know what the antiderivate of 3sinxcosx is and yes I am integrating from crud hold up let me find it. Got hazelnut on my fingers

Answer 7

is it : \(\frac{-3}{2}cos^2x\) ?

Answer 8

OH + C there also

Answer 9

\[\int\limits_{}^{}3sinxcosx~dx \\ \\ Let~u=sinx \\ \\du=cosx~dx \\ \\ Then, \\ \\ \int\limits_{}^{}3u~du \\ \\ Integrate\]

Answer 10

@UsukiDoll you were at right process.

Answer 11

@mathslover oh sry didn't see your comment there.

Answer 12

:) No problem @.Sam. , it is so nice of you to even say "sry" no mistake of yours' .

Though, can you tell whether I am correct or not (scroll up to see my answer)

Answer 13

\[\int\limits_{0}^{\frac{\pi}{2}}\] 3cos(x)sin(x)dx=\[\frac{3}{2}\]

Answer 14

I need the antiderivative of 3sinxcosx integrating from pi/2 to 0. umm that's what I did. like u sinx du cosx and then it's 3/2 u^2 but for some reason my manual has it at 3/2 sin2t. ummm WHAT!

Answer 15

@UsukiDoll ok got it

Answer 16

@mathslover am i right

Answer 17

sin^2t maybe but sin2t? what the heck

Answer 18

==lol

Answer 19

@mathslover yes you are

Answer 20

why not just u=sinx so du=cosxdx ???

Answer 21

ummm that's what I did bytemr

Answer 22

oops yes a =0 b = pi/2

Answer 23

lol.... you said my name...

Answer 24

loloolol

Answer 25

I could've sworn it was like this...

Answer 26

3sinx cos x = 3/2 sin 2x
does this ring the bell ?

Answer 27

Why is it sinx 2x?!?!?!?!?!?!?!!?

Answer 28

is there an identity that I missed @hartnn

Answer 29

double angle formula:
sin 2x = 2 sin x cos x
cos 2x = cos^2 x- sin^2 x
= 2cos^2x -1
= 1-2sin^2 x

Answer 30

yeah but that 2sinxcosx not 3sinxcosx and why is the 2 below the 3 in this one?

Answer 31

@mathslover you were typing something ?
3sin x cos x = 3/2 (2sin x cos x) = 3/2 sin 2x

Answer 32

its antiderivative will be -3/4 cos 2x

Answer 33

again what I don't understand is why the 3/2? the problem is 3sinxcosx. There is no 2sinxcosx. so what Do i DO?

Answer 34

so u did not understand this ? 3sin x cos x = 3/2 (2sin x cos x)
i just multiplied and divided by 2

Answer 35

ohhhhh..... -___-

Answer 36

that's legal? multiplying 2 and dividing 2?

Answer 37

absolutely!
because 2 is constant.

Answer 38

O______O!

Answer 39

ummm what math class is this normally in? Is it in trig?

Answer 40

those double angle formulas? in trignometry..

Answer 41

no about the 3/2 2sinxcosx

Answer 42

its general, no particular topic, u can do that anytime, anywhere...

Answer 43

THE HECK?

Answer 44

I got one more...so I'm opening a new question.

Answer 45

ok.