SOLUTION: In an a.p, the sum of first 11 terms is 44 and that of next 11 terms is 55 find the first term and common diffrence
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Question 851565: In an a.p, the sum of first 11 terms is 44 and that of next 11 terms is 55 find the first term and common diffrence Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! S = ½(2a1 + d(n-1))n
44 = ½(2a + d(10))11,
8=2a+10d
9 = (2a + d(21))
9=2a+21d,
8=2a+10d
9=21d
8=10d
1=11d
1/11=d
8=2a+10d
8=2a+10/11
4=a+5/11
39/11=a
first term is 39/11
difference is 10/11
check
44 = ½(2a + d(10))11
44=1/2(2*39/11+10/11)*11
ok
