Suppose Your Newspaper Is Trying to Decide Between Two Competing $U ( x , y ) = 8 x ^ { 0.9 } y ^ { 0.1 } + x$

Multiple Choice

Suppose your newspaper is trying to decide between two competing desktop publishing software packages, Macro Publish and Turbo Publish. You estimate that if you purchase x copies of Macro Publish and y copies of Turbo Publish, your company's daily productivity will be $U ( x , y ) = 8 x ^ { 0.9 } y ^ { 0.1 } + x$
Where U (x, y) is measured in pages per day (U is called a utility function.) If $x = y = 9$ , by approximately how many pages per day will productivity increase if x is increased by one unit

A) A productivity increase of approximately 7.16 pages per day.
B) A productivity decrease of approximately 81.00 pages per day.
C) A productivity increase of approximately 89.16 pages per day.
D) A productivity increase of approximately 16.32 pages per day.
E) A productivity increase of approximately 8.16 pages per day.