213/2+5n 9. Find lim log sec Show all work to receive credit. 12-00 n+7 10. Find limn cos n cos(n) Show all work to receive credit. 818 72 11. Find (a) the interval of convergence, and (b) the sum, expressed in terms of x, for the following series. 1 x+ 8 2 12. Express the given series using summation notation. 1 2 3 --- + 4 + 2 5 8 11 +