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Multiple Choice
Evaluate the line integral , where C is the curve given by , , for .
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Verified step by step guidance
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Step 1: Recall the formula for a line integral with respect to arc length: \( \int_C f(x, y) \, ds \). Here, \( f(x, y) = \frac{x}{y} \), and \( ds \) is the differential arc length, which can be expressed as \( ds = \sqrt{\left( \frac{dx}{dt} \right)^2 + \left( \frac{dy}{dt} \right)^2} \, dt \).
Step 2: Parameterize the curve \( C \) using the given equations \( x = t^3 \) and \( y = t^4 \), where \( t \) ranges from 1 to 2. Compute the derivatives \( \frac{dx}{dt} = 3t^2 \) and \( \frac{dy}{dt} = 4t^3 \).
Step 3: Substitute \( \frac{dx}{dt} \) and \( \frac{dy}{dt} \) into the formula for \( ds \): \( ds = \sqrt{(3t^2)^2 + (4t^3)^2} \, dt = \sqrt{9t^4 + 16t^6} \, dt = \sqrt{t^4(9 + 16t^2)} \, dt = t^2 \sqrt{9 + 16t^2} \, dt \).
Step 4: Substitute \( x = t^3 \), \( y = t^4 \), and \( ds = t^2 \sqrt{9 + 16t^2} \, dt \) into the line integral: \( \int_C \frac{x}{y} \, ds = \int_1^2 \frac{t^3}{t^4} \cdot t^2 \sqrt{9 + 16t^2} \, dt = \int_1^2 \frac{1}{t} \cdot t^2 \sqrt{9 + 16t^2} \, dt \).
Step 5: Simplify the integrand: \( \int_1^2 t \sqrt{9 + 16t^2} \, dt \). This integral can now be evaluated using substitution or other integration techniques, but the setup is complete.