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Multiple Choice
Given , where and , use the chain rule to find the partial derivatives and .
A
= , =
B
= , =
C
= , =
D
= , =
Verified step by step guidance
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Step 1: Start by identifying the given function z = (x - y)^9, where x = s^2 t and y = s t^2. The goal is to compute the partial derivatives ∂z/∂s and ∂z/∂t using the chain rule.
Step 2: Apply the chain rule for ∂z/∂s. The chain rule states that ∂z/∂s = ∂z/∂x * ∂x/∂s + ∂z/∂y * ∂y/∂s. First, compute ∂z/∂x and ∂z/∂y by differentiating z = (x - y)^9 with respect to x and y, respectively. This gives ∂z/∂x = 9(x - y)^8 and ∂z/∂y = -9(x - y)^8.
Step 3: Compute ∂x/∂s and ∂y/∂s. From x = s^2 t, differentiate with respect to s to get ∂x/∂s = 2s t. From y = s t^2, differentiate with respect to s to get ∂y/∂s = t^2.
Step 4: Substitute the values of ∂z/∂x, ∂z/∂y, ∂x/∂s, and ∂y/∂s into the chain rule formula for ∂z/∂s. This results in ∂z/∂s = 9(x - y)^8 * (2s t - t^2).
Step 5: Repeat the process for ∂z/∂t. Apply the chain rule: ∂z/∂t = ∂z/∂x * ∂x/∂t + ∂z/∂y * ∂y/∂t. Compute ∂x/∂t = s^2 and ∂y/∂t = 2s t. Substitute these values along with ∂z/∂x and ∂z/∂y into the formula to get ∂z/∂t = 9(x - y)^8 * (s^2 - 2s t).