faustprouvaire replied to your post: hey can someone give me some calc help for a…
What’s the problem?
ugh I’m just working through all the problems on this study sheet and there are a lot of ‘tricks’ that you need to know and I don’t know them and I keep getting stuck/getting the wrong answers
We should try this problem because reasons: Express the indefinite integral
in terms of elementary functions. Use the symbol C to denote an arbitrary constant.
I stared at this and then it hit me like a brick (basically getting hit by 1000+ book about awesome french people really hurts).
Your U is cosx. The derivative of cosx is -sinx. So you get:
The 2 goes in front of the integral because it’s a constant and it is negative because of -sinx.
Remember the integration power rule is:
so we get:
[there should be a negative in front of the 2 but I’m too tired to mess with latex.]
Now after integrating we get:
If we put cosx back in for U, we get:
don’t forget the C because it’s an indefinite. This answer is in agreement with RPI’s answer
The rest of the problems can be pretty much solved in a similar way. For definite integral, it’ll be helpful to know the cos of pi/2 is 0, pi is 1 and the cos and sin of pi/4 is .