Line integral please help http://prntscr.com/6nkvwg

Question

jhannybean · Answer

@wio >:)

anonymous · Answer

try using https://www.wolframalpha.com/

thefurball · Answer

can you do line integrals there? haven't tried

thefurball · Answer

I do need to learn this though lol

anonymous · Answer

furball, do you need help with a parametrization?  What is troubling you?

anonymous · Answer

i dont know it just might help

thefurball · Answer

I can parameterize them into to different things. I'm just lost from there.

rational · Answer

|dw:1427782105472:dw|

anonymous · Answer

To parametrize between two points $p$ and $q$, you can use this formula: $$
r(t) =(q-p)t + p,\quad t\in [0,1]
$$Because it gives you $r(0) = p$ and $r(1) = q$.

anonymous · Answer

Give me your parametrization then.

thefurball · Answer

was thinking $$C _{1}: x=4t, y=t$$$$C _{2}: x = t+4, y =1-t$$? That's what I've been doing with line integrals so far

anonymous · Answer

That will work.

thefurball · Answer

Ok. What do I plug in for dx and dy?

anonymous · Answer

Well, for the first one: $$
dx  = d(4t) = 4~dt\
dy = d(t) = dt
$$

anonymous · Answer

For the second one: $$
dx = d(t+4) = dt\
dy = d(1-t) = -dt
$$

anonymous · Answer

We are using: $$
dx = x'(t)~dt =\frac{dx}{dt}dt
$$

anonymous · Answer

Are you still stuck?

thefurball · Answer

Got it! Sorry, was working on it lol. Thanks a lot!