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In what directions is the derivative of f(x,y) = xy + y at P(9,5) equal to zero? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. u= (Simplify your answer. Use a comma to separate answers as needed. Type your answer in terms of i and j.) O B. There is no solution.Find a parametric equation for the line that is perpendicular to the graph of the equation 4x" + 4y - +32- = 32 at the point (2, 1,2). r(t) = ( pi + j + jk (Type expressions using t as the variable. )Find the gradient of the function f(x,y) = 10y - 6x at the point (7,10). Then sketch the gradient and the level curve that passes through that point. Vf|(7,10) = i + (Simplify your answer.)Find the gradient of the function g(x,y) = xy at the point (1, -2). Then sketch the gradient together with the level curve that passes through the point.Find the gradient of the function f(x,y) = 2x+ 4y at the point (-2,2). Then sketch the gradient together with the level curve that passes through the point.Find Vf at the given point. 3 3 f( x, y,z) = x + v - 2z + z Inx, (1,4,5) VF(1,4.5) = )k (Simplify your answers.)