integral of sin(2x)dx


by physx_420
Tags: -cos(x), differentation, integral, sin(x)
physx_420
physx_420 is offline
#1
Apr4-10, 09:09 PM
P: 33
1. The problem statement, all variables and given/known data
[tex]\int[/tex] sin(2x)dx


2. Relevant equations
I know the integral of sin(x)dx = -cos(x) + C


3. The attempt at a solution
What I did was to say that the integral is -cos(2x) +C, which isn't the correct answer...I should have gotten -1/2(cos(2x)) +C. I can see that this is the correct answer when I differentiate it via chain rule and get sin(2x), however I can't seem to integrate the problem to get the right answer. Can someone walk me through it please.....
Phys.Org News Partner Science news on Phys.org
Cougars' diverse diet helped them survive the Pleistocene mass extinction
Cyber risks can cause disruption on scale of 2008 crisis, study says
Mantis shrimp stronger than airplanes
Mark44
Mark44 is offline
#2
Apr4-10, 09:35 PM
Mentor
P: 21,062
Use substitution, with u = 2x, du = 2dx. Integration by substitution is the reverse of the chain rule in differentiation.
physx_420
physx_420 is offline
#3
Apr4-10, 09:49 PM
P: 33
ah so that's where I went wrong....I tried u substitution but I used u=sin2x instead of u=2x. thanks mark44.


Register to reply

Related Discussions
Is the ordinary integral a special case of the line integral? Calculus 3
volume integral to spherical coords to contour integral Calculus & Beyond Homework 4
Is Cauchy's integral formula applicable to this type of integral? Calculus & Beyond Homework 4
Sine integral (sinc integral) question Calculus & Beyond Homework 3
Length of the curve integral, can't solve the integral Calculus & Beyond Homework 2