The common difference of an A.P is -2.find it\'s sum,if first term is 100and last term is-10.

The common difference of an A.P is -2.find it\'s sum,if first term is

1.	The common difference of an A.P is -2.find it\'s sum,if first term is 100and last term is-10.
Answer» 2520 Varun pornia your answer is wrong The formula of sn is ~1/2{2a+(n-1)d} And another formula is sn~{1/2(a+l)} So\' I use second formula Given; a=100 l=10 Put value in formula; we get 1/2 (100+10) = 1/2×110 =55 is anwer 152