differentiation and integration

I am reallly confused with this question, it seems so easy, but i still don't know what it is

the question is:

if dy/dx= cos3x and y=1 when x=0, find y when x=pi/4. I know the answer is supposed to be negative sqrt 0.5 but how to get there is whats confusing me.

Can someone please explain?

Please and thank you

Re: differentiation and integration

Quote:

Originally Posted by

**supp** I am reallly confused with this question, it seems so easy, but i still don't know what it is

the question is:

if dy/dx= cos3x and y=1 when x=0, find y when x=pi/4. I know the answer is supposed to be negative sqrt 0.5 but how to get there is whats confusing me.

Can someone please explain?

Please and thank you

sub in the given values for x and y and solve for the constant of integration ... then evaluate the function at