3. (15 points) Using the same function as the previous question, f(r, y) = In(x2 + y), answer the following questions: (a) Determine Duf(2,3) with v = (4, 5) (b) What is the angle, in radians, between v and Vf(2, 3)?4. (15 points) Wheat production, W, in Bushels/Acre is a function of temperature T in 'C and annual rainfall, R in centimeters. Suppose that scientists observe that average temperature is increasing by 0.15C/year and rainfall is aw decreasing by 0.10 cm/year. Further, it is estimated that aw = -2 and = 8. aT OR aw (a) Explain, in one or two sentences, ye meaning/significance of : -2. aT aw (b) Explain, in one or two sentences, the meaning/significance of OR = 8 dw (c) Compute the current rate of change of wheat production, (t is time in years) dt