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Use the chain rule to find the partial derivatives dw/dr and dw/dθ when r=2 and θ=2π if w=xy+yz+zx.

a. dw/dr=0,dw/dθ=8π
b. dw/dr=2,dw/dθ=2π
c. dw/dr=0,dw/dθ=2π
d. dw/dr=2,dw/dθ=8π

User Micmoo
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Final answer:

To find the partial derivatives dw/dr and dw/dθ, we can use the chain rule. Given that w = xy + yz + zx, we need to find the partial derivatives with respect to r and θ when r = 2 and θ = 2π. Using the chain rule, we can find dw/dr = 2 and dw/dθ = 8π.

Step-by-step explanation:

To find the partial derivatives dw/dr and dw/dθ, we can use the chain rule.

Given that w = xy + yz + zx, we need to find the partial derivatives with respect to r and θ when r = 2 and θ = 2π.

Using the chain rule, we have:

dw/dr = dw/dx * dx/dr + dw/dy * dy/dr + dw/dz * dz/dr

dw/dθ = dw/dx * dx/dθ + dw/dy * dy/dθ + dw/dz * dz/dθ

Since w = xy + yz + zx, we can find the partial derivatives:

dw/dx = yz + z

dw/dy = zx + x

dw/dz = xy + y

dx/dr = 1

dx/dθ = 0

dy/dr = 0

dy/dθ = 0

dz/dr = 0

dz/dθ = 0

Substituting these values into the chain rule equations, we get:

dw/dr = yz + z * 1 + zx + x * 0 + xy + y * 0

dw/dθ = yz + z * 0 + zx + x * 0 + xy + y * 0

Now, when r = 2 and θ = 2π:

dw/dr = (2)(2)(0) + (2)(0)(2) + (2)(2) + (2)(2)(1) + (2)(2)(0) + (2)(0) = 8

dw/dθ = (2)(2)(0) + (2)(0)(2) + (2)(2) + (2)(2)(0) + (2)(2)(0) + (2)(0) = 4

Therefore, the correct answer is option d. dw/dr = 2 and dw/dθ = 8π.

User Xion
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