Question

Calc 3 just need help with one last question due in 20 minutes!!! please help!

Answer 1

try ask in math stackexchange

Answer 2

7 times already?

Answer 3

you need some help

Answer 4

yeah i dont know what to do?

Answer 5

so whats your guess?

Answer 6

i tried doing the area of the trapezoid but that didnt work

Answer 7

i dont think its looking for an area, but rather a line integral

Answer 8

what do i do?

Answer 9

for me to be sure, can you tell me the topic that is involved? im only guessing it to be a line integral and ive been known to be wrong :)

Answer 10

have you done integrals over a vector field before?

Answer 11

F = < sinx+4y , 8x+y >

and you need to define each line segment as a vector equation to define x and y

Answer 12

i dont know what to do, i think we have done line integrals

Answer 13

like A to B

<0,0> +t<1,1>; x=t, y=t for t=0 to 1

r<t,t>; r'=<1,1>

FF = < sint+4t , 8t+t >
dot r' = < 1 , 1 >
---------------------------
sint+4t + 8t+t

\[\int_{0}^{1}~sint+4t + 8t+t ~dt\]

Answer 14

or at least thats my interpretation of what you posted

Answer 15

im confused what about when the x and y values are different?

Answer 16

if this is a line integral, then we want to define x and y in terms of a common variable; a vector equation allows us to define and and y in terms of say, t

Answer 17

so what would you say the answer is

Answer 18

then we replace x and y with their respective t equivalents, and dot the function with the derivative of the vector line equation that we got x and y from

Answer 19

i dunno yet; there are 3 line segments to work thru and then add up; assuming ive got the right idea to begin with

Answer 20

http://tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsVectorFields.aspx

this seems to be a good and easy read of what im thinking of

Answer 21

does the answer have to be exact or approximate?

Answer 22

exact i think

Answer 23

my concern is i have never seen or played with a function defined in dx dy terms so i have to wonder if my first thought is even correct to begin with. It would be helpful if you could give more context for the problem.