Suppose the Utility Function $U = f ( x , y ) \text { is a measure of the utility (or satisfaction) }$

Multiple Choice

Suppose the utility function $U = f ( x , y ) \text { is a measure of the utility (or satisfaction) }$ derived by a person from the consumption of two products x and y. Determine the marginal utility of product $x$ if the utility function is $U = - 5 x ^ { 2 } + x y - 7 y ^ { 2 }$ .

A) $U _ { x } = - 7 x + y$
B) $U _ { x } = - 9 x - y$
C) $U _ { x } = - 10 x + y$
D) $U _ { x } = - 14 x - y$
E) $U _ { x } = - 11 x + y$