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Let f(x,y)=x2−xy+y2−y. Find the directions u and the values of Du​f(1,−1) for which the following is true. a. Du​f(1,−1) is largest b. Du​f(1,−1) is smallest c. Du​f(1,−1)=0 d. Du​f(1,−1)=4 e. Du​f(1,−1)=−3 a. Find the direction u and the value of Du​f(1,−1) for which Du​f(1,−1) is largest. u=□i+(□)j
In what directions is the derivative of f(x,y)=xy+y2 at P(1,6) equal to zero? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A. u= (Simplify your answer. Use a comma to separate answers as needed. Type your answer in terms of i and j.) B. There is no solution.
Find a parametric equation for the line that is perpendicular to the graph of the equation x2+4y2+3z2=17 r(t)=(□)i+(□)j+k