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Multiple Choice
Given and , find and in terms of .
A
, =
B
, =
C
, =
D
, =
Verified step by step guidance
1
Step 1: Start by finding dx/dt and dy/dt. Since x = e^t, differentiate x with respect to t to get dx/dt = e^t. For y = t e^{-t}, use the product rule to differentiate y with respect to t: dy/dt = d(t)/dt * e^{-t} + t * d(e^{-t})/dt = 1 * e^{-t} + t * (-e^{-t}) = e^{-t} - t e^{-t}.
Step 2: To find dy/dx, use the chain rule: dy/dx = (dy/dt) / (dx/dt). Substitute dy/dt = e^{-t} - t e^{-t} and dx/dt = e^t into the formula: dy/dx = (e^{-t} - t e^{-t}) / e^t. Simplify the expression by combining the exponents: dy/dx = (1 - t) / e^{2t}.
Step 3: To find d^2y/dx^2, first compute d(dy/dx)/dt. Differentiate dy/dx = (1 - t) / e^{2t} with respect to t using the quotient rule: d(dy/dx)/dt = [(d(1 - t)/dt) * e^{2t} - (1 - t) * d(e^{2t}/dt)] / (e^{2t})^2. Simplify each term: d(1 - t)/dt = -1, and d(e^{2t})/dt = 2 e^{2t}.
Step 4: Substitute the simplified derivatives into the formula for d(dy/dx)/dt: d(dy/dx)/dt = [(-1) * e^{2t} - (1 - t) * 2 e^{2t}] / e^{4t}. Combine terms in the numerator: d(dy/dx)/dt = [-e^{2t} - 2 e^{2t} + 2t e^{2t}] / e^{4t} = (-3 + 2t) / e^{2t}.
Step 5: To find d^2y/dx^2, divide d(dy/dx)/dt by dx/dt: d^2y/dx^2 = [(-3 + 2t) / e^{2t}] / e^t. Simplify the expression by combining the exponents: d^2y/dx^2 = (2t - 3) / e^{3t}.