Let $f(x,y)=-(2sin(x{y}^2)cos(y-x)).$ Calculate gradf.

gradf$(x,y)=($:$,-4ycos(x{y}^2)sin(y-x)$:$)$

What is the directional derivative of $z=f(x,y)=-(2sin(x{y}^2)cos(y-x))$ in the direction of the vector vec$(v)=-ij?$ Put your formula into either exact form, or round all numerical values to at least $3$ decimal places.

$f_{\text{v}\text{e}\text{c}(v)}(x,y)=5$

What is the directional derivative of $z=f(x,y)=-(2sin(x{y}^2)cos(y-x))$ at the point $(3,3)$ in the direction of the vector vec$(v)=-ij?$ Round your answer to at least $3$ decimal places.

$f_{\text{v}\text{e}\text{c}(v)}(3,3)=$

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