Define Yn = (2n) 4-", Zn = 2-4-6-... (2n) 1-3-5... (2n-1)* Select those statements below which give a correct justification of the monotonic behaviour of the sequences (yn) and (Zn) 1 We have We have We have We have increasing. We have decreasing. We have We have Yn+1 Yn We have Zn+1 Zn Zn+1 Zn Yn+1 Yn Zn+1 Zn Zn+1 Zn Yn+1 Yn Yn+1 Yn = = = = = = = = 2n+1 n+1 2n+2 2n+1 > 1, so (yn) is strictly increasing. 8 n=1 > 1, for all n E N, so (Zn) is strictly increasing. n=1 (2n+1)(2n+2) 2n+2 (2n)(2n+1) 2n (2n+2)(2n+1) 4(n+1) 2n+2 2n+1 (2n+1)(2n+2) (2n)(2n+1) 2n+1 4(n+1) = 2n+1 4(n+1) = = 2n+1 2n+2 2n+2 2n > 1, for all n N, so (Z) is strictly n=1 < 1, for all n < 1, so (yn) > 1, so (y) < 1, so (yn) is strictly decreasing. n=1 > 1, for all n E N, so (Zn) is strictly n=1 N, so (Zn) is strictly decreasing. n=1 is strictly decreasing. is strictly increasing