For Function $f ( x , y ) = 8 - \frac { x } { 8 } - \frac { y } { 7 } , \text { find the maximum value of the directional }$

question 31

Multiple Choice

For function $f ( x , y ) = 8 - \frac { x } { 8 } - \frac { y } { 7 } , \text { find the maximum value of the directional }$ derivative at (3,2) .

• A) \(\sqrt { 15 } / 8\)
• B) \(\sqrt { 113 } / 56\)
• C) \(\sqrt { 113 } / 224\)
• D) \(\sqrt { 113 } / 112\)
• E) \(\sqrt { 113 } / 168\)