Question 1015834
∂u/∂x={{{e^x/(e^x+e^y)}}}
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∂u/∂y={{{e^y/(e^x+e^y)}}}
So then adding them together,
∂u/∂x+∂u/∂y={{{(e^x+e^y)/(e^x+e^y)=1}}}