Find the Directional Derivative Of $f ( x , y ) = 20 \sqrt { x } - y ^ { 3 }$

question 10

Multiple Choice

Find the directional derivative of $f ( x , y ) = 20 \sqrt { x } - y ^ { 3 }$ at the point (1, 3) in the direction toward the point (3, 1) .

• A) \(37 \sqrt { 2 }\)
• B) \(\frac { 37 } { \sqrt { 2 } }\)
• C) \(\sqrt { 2 }\)
• D) \(37\)
• E) None of these

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