Partial Derivative with Respect to y of a*cos(xy)-y*sin(xy)

[Math10]

Homework Statement

Find the partial derivative of a*cos(xy)-y*sin(xy) with respect to y.

Homework Equations

None.

The Attempt at a Solution

The answer is -ax*sin(xy)-sin(xy)-xy*cos(xy).
I know that I need to treat x as constant since I need to take the partial derivative with respect to y. But I don't know how to get -sin(xy). I know how to get -ax*sin(xy) and -xy*cos(xy).

 

[Math10]

Never mind. I got it.

 

[Math10]

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