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38. DETAILS MY NOTES | ASK YOUR TEACHEF Bicycles. A local company that manufactures and sells bikes has found that its monthly revenue (in dollars) is given by R(x,y) = 5 x2 2.5 y2 5 xy + 600 x + 320 y where X is the number of mountain bikes and y is the number of city bikes that it sells each month. (a) The critical point of R(x,y) is 0 (8,56) 0 (56,8) 0 (40,60) 0 (60,40) 0 (90,15) 0 (15,90) 0 There is no critical point 0 (0,0) (b) Let D(X,y)=Rxx(x,y)Ryy(X,y)ny2(x,y). Suppose that a is the number of mountain bikes and b is the number of city bikes that should be sold each month to ensure a maximum monthly revenue. Which of the following statements is true? 0 (303,50 > 0 and Rxx(a,b) 0 and Rxx(a,b) > 0 O D(a,b) = 0 O D(a,b) 0 \f39. DETAILS Derivative. The derivative of 64 h(x) = 2 + e(4x2 + 3) is 2 2 e4(_4)(2 + e(4X + 8))_e(4X + 8)(8X)(e4) O h'(x) = 2 (2 + 8(4X + 8))2 0 none of the other answers 2 _e(4X + 8)(8X)(e4) O h'(x) = 2 (2 + e(4X +3))2 2 2 e4(_4)(2 + e(4X + 8))_e(4X + 8)(8X)(e4) O h'(X) = 2 (2 + 9(4X + 8))