A competitive firm's production function is f(x1,x2)=8x1^(1/2)+8x2^(1/2). The price of factor 1 is $1 and the price of factor 2 is $3.

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1. A competitive firm's production function is f(x1,x2)=8x1^(1/2)+8x2^(1/2). The price of factor 1 is $1 and the price of factor 2 is $3. The price of output is $6. What is the profit-maximizing quantity of output?