Evaluate the line integral over C ∫(x + y)ds where C is the line segment from (0,1,1) to (3,2,2). I've parameterized C as 3ti + (1+t)j + (1+t)k, and I get the result 3√(11). Is that correct? Thanks!!

Respuesta :

Answer:

Yes, you are correct!!!

The result is [tex]\int\limits^{1}_{0} {4t+1dt} \,=3\sqrt{11}[/tex]

Step-by-step explanation:

The given line integral is

[tex]\int\limits_C {x+y} \, ds[/tex], where C is the line segment from [tex](0,1,1)[/tex] to [tex](3,2,2)[/tex].

First we need to get the direction vector,

[tex]d=\:<\:3,2,2\:>-\:<\:0,1,1\:>[/tex]

[tex]d=\:<\:3,1,1\:>[/tex]


The parametric equation now becomes,

[tex]r(t)=\:<\:0,1,1\:>+\:t<\:3,1,1\:>[/tex].

[tex]\Rightarrow r(t)=3ti+(1+t)j+(1+t)k[/tex].


We parameterize the curve with the equations,

[tex]x=3t[/tex] and [tex]y=t+1[/tex]


[tex]ds=|r'(t)|dt[/tex]

[tex]\Rightarrow ds=|3i+j+k|dt[/tex]


[tex]\Rightarrow ds=\sqrt{3^2+1^2+1^2}dt[/tex]


[tex]\Rightarrow ds=\sqrt{11}dt[/tex].

The line integral now becomes,


[tex]\int\limits^{1}_{0} [{3t+(t+1)]\sqrt{11}dt} \,[/tex]


[tex]\sqrt{11}\int\limits^{1}_{0} {4t+1dt} \,=3\sqrt{11}[/tex]









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