Consider the differential equation &x = d = yx+ y . Lety = f(x) be the particular solution to the differential equation with initial condition f(0) = 1. 60. (a) Find dy in terms of x and y . Is y concave up or concave down at f(0) ? Justify your conclusion. 61. (b) Use Euler's method, starting at x = 0 with two steps of equal size, to approximate f(2) . 62. (c) Find y = f(x) , the particular solution to the differential equation with initial condition f(0) = 1Lills exam Consider the following series: 1/3 n 63. (a) For what values of t does this series converge? Justify your answer. 64. (b) Show that the ratio test is inconclusive when t = 3. 65. (c) What is the sum of the first 3 nonzero terms when t = 6? 66. (d) Using the Comparison test, justify whether the following series converges or diverges: 700 In = 1 n 2/3 - 7