Let $f ( x , y ) = \sqrt { x ^ { 2 } + y ^ { 2 } }$ . Then the maximum value of the directional derivative $D _ { \mathrm { u } } f ( 2,4 )$ is

A) $\sqrt { 3 }$
B)2
C)3
D)1
E)5

Question

Let $f ( x , y ) = \sqrt { x ^ { 2 } + y ^ { 2 } }$ . Then the maximum value of the directional derivative $D _ { \mathrm { u } } f ( 2,4 )$ is

A) $\sqrt { 3 }$
B)2
C)3
D)1
E)5

Quizplus · Accepted Answer

The Answer of Let $f ( x , y ) = \sqrt { x ^ { 2 } + y ^ { 2 } }$ . Then the maximum value of the directional derivative $D _ { \mathrm { u } } f ( 2,4 )$ is

A) $\sqrt { 3 }$
B)2
C)3
D)1
E)5

Let f(x,y)=x2+y2f ( x , y ) = \sqrt { x ^ { 2 } + y ^ { 2 } }f(x,y)=x2+y2​

Let $f ( x , y ) = \sqrt { x ^ { 2 } + y ^ { 2 } }$