Hello everyone, I am reviewing for my vector calculus exam and one of the line integral problems my professor recommended us to look over isn't like any of the other problems I have done, so could someone please tell me how to solve this. (The answer to this problem is 2.8)
Here is the problem:
Compute the line integral of the scalar function over the curve:
f(x, y) = sqrt(1+9xy) y = x^3 for 0<=x<=1
I know that the formula for this type of question is:
ɾ
| f(c(t)) ||c'(t)|| dt
ᴊ C
but I'm not sure how to solve this if I don't know c(t), so could someone please help me out with this because I'm very confused. (I only need to know how to find c(t))
Thanks,
Kevin
Here is the problem:
Compute the line integral of the scalar function over the curve:
f(x, y) = sqrt(1+9xy) y = x^3 for 0<=x<=1
I know that the formula for this type of question is:
ɾ
| f(c(t)) ||c'(t)|| dt
ᴊ C
but I'm not sure how to solve this if I don't know c(t), so could someone please help me out with this because I'm very confused. (I only need to know how to find c(t))
Thanks,
Kevin
-
To find c(t), you will need to parametrize the curve.
Since y = x^3 for 0 <= x <= 1, we can use x = t, y = t^3, 0 <= t <= 1.
Thus we can use c(t) = for 0 <= t <= 1.
So the line integral of f(x, y) = sqrt(1+9xy) along the curve is
integral 0 to 1 of f(t, t^3) ||d/dt of|| dt
= integral 0 to 1 of sqrt(1+9t*t^3) ||<1, 3t^2>|| dt
= integral 0 to 1 of sqrt(1+9t^4) * sqrt(1^2+(3t^2)^2) dt
= integral 0 to 1 of sqrt(1+9t^4) * sqrt(1+9t^4) dt
= integral 0 to 1 of (1+9t^4) dt
= (t + (9/5)t^5) evaluated from t = 0 to t = 1
= (1 + (9/5)(1^5)) - (0 + (9/5)(0^5))
= 14/5
= 2.8
Lord bless you today!
Since y = x^3 for 0 <= x <= 1, we can use x = t, y = t^3, 0 <= t <= 1.
Thus we can use c(t) =
So the line integral of f(x, y) = sqrt(1+9xy) along the curve is
integral 0 to 1 of f(t, t^3) ||d/dt of
= integral 0 to 1 of sqrt(1+9t*t^3) ||<1, 3t^2>|| dt
= integral 0 to 1 of sqrt(1+9t^4) * sqrt(1^2+(3t^2)^2) dt
= integral 0 to 1 of sqrt(1+9t^4) * sqrt(1+9t^4) dt
= integral 0 to 1 of (1+9t^4) dt
= (t + (9/5)t^5) evaluated from t = 0 to t = 1
= (1 + (9/5)(1^5)) - (0 + (9/5)(0^5))
= 14/5
= 2.8
Lord bless you today!