7. For the function f(x, y) = ox -y . Find the directional derivative Dy f at the point A(3, 2) in the direction of vector V =4i +3j 8. The pressure profile, in /b/in', for a particular surface is defined as: P(x, y, =) = /x* + y- +2 . Find the rate of change of the pressure from point A(1, 2, - 2) to B(-5,8, -5). 9. The pollution concentration at a lake follows the expression (x, y,=) =0.01 e(*)*=). Determine the vector pointing to the direction of greatest pollution increase at the point (1,2,3) . And then use the direction cosines to determine the 3 direction angles. 10. The wind speed profile at a particular location is defined as W(x, y) =50-x -4y. A sensor is placed at (2,-1). What direction of largest wind increase will the sensor detect? Relative to North, what is this direction in degree