Find the Largest Value of the Directional Derivative of the Function

question 131

Multiple Choice

Find the largest value of the directional derivative of the function $f ( x , y ) = \frac { y } { x + y }$ at the point $( x , y ) = ( 1,2 )$ .

• A) \(\sqrt { 5 }\)
• B) \(\frac { 5 } { 9 }\)
• C) \(- \sqrt { 5 }\)
• D) \(- \frac { 5 } { 9 }\)
• E) \(\frac { \sqrt { 5 } } { 3 }\)
• F) \(\frac { \sqrt { 5 } } { 9 }\)
• G) \(- \frac { \sqrt { 5 } } { 3 }\)
• H) \(- \frac { \sqrt { 5 } } { 9 }\)

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