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The divergence of the vector field u = e^x(cos y î + sin y ĵ) is

1. 0
2. e^x cos y + e^x sin y
3. 2e^x cos y
4. 2e^x sin y

Correct answer: 2e^x cos y

Solution

div u = d/dx(e^x cos y) + d/dy(e^x sin y) = e^x cos y + e^x cos y = 2 e^x cos y. The stored single-term expression is incorrect.

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