Find the Directional Derivative of the Function $f ( x , y ) = x ^ { 2 } + y ^ { 2 }$

question 66

Multiple Choice

Find the directional derivative of the function $f ( x , y ) = x ^ { 2 } + y ^ { 2 }$ at the point $( 1,1 )$ in the direction $\theta = \frac { \pi } { 4 }$ .

• A) \(\sqrt { 2 }\)
• B) \(2 \sqrt { 2 }\)
• C) \(4 \sqrt { 2 }\)
• D) \(\frac { 1 } { \sqrt { 2 } }\)
• E)1
• F)2
• G)4
• H)
• \(\frac { 1 } { 2 }\)

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