Question:Find the sum of first 22 terms of the AP: 8, 3, -2, .....A-899B-1010C-979D-880Answer: C. -979Explanation:a=8,d=3−8=−5,n=22a=8,d=3-8=-5,n=22a=8,d=3−8=−5,n=22Sn=n/2(2a+(n−1)d)S_n=n/2(2a+(n-1)d)Sn=n/2(2a+(n−1)d)S22=22/2×(2×8+(22−1)×−5S_{22}=22/2\times(2\times8+(22-1)\times-5S22=22/2×(2×8+(22−1)×−5=11(16+21×−5=11(16+21\times-5=11(16+21×−5=11×−89=11\times-89=11×−89=−979=-979=−979
