Question

What is the Integral for cos3xdx??

Answer 1

seperate it into sin and cos parts ...

Answer 2

im assuming that cos^3 (x) hard to read when people dont make use of grouping symbols

Answer 3

Sorry, it's cos(3x)dx....

Answer 4

ah, even simpler then

Answer 5

we know that this had to come from some version of sin(3x) right?

Answer 6

Okay

Answer 7

lets tack on a constant scalar:\[k~\sin(3x)\]
and take the derivative to compare it against what you have

Answer 8

what would we get for this derivative?

Answer 9

What about 3 sin (3x) ?

Answer 10

hmm, lets try that out:

3 sin(3x) derives to 3*3 cos(3x) = 9 cos(3x)

9 cos(3x) is not equal to cos(3x)

Answer 11

Mmmm, then 1/3 sin(3x) I presume?

Answer 12

if we take the derivative of: k sin(3x) we obtain

k sin(3x) derives to 3k cos(3x)

3k cos(3x) = cos(3x) when 3k = 1

so yeah :)

Answer 13

Awesome!!! Thanks a lot amistre64!!!

Answer 14

youre welcome