Posted by akash on Tuesday, February 28, 2012 at 3:32am.
.
nth term is a+(n-1)d
sum of 1st n terms = n/2(T1+Tn)
a = 2
sum of 1st 5 terms = 5/2 (2 + 2+4d) = 10+10d
6th term = 2+5d
sum of terms 6-10 = 5/2 (2+5d + 2+9d) = 10+35d
10+10d = 1/4 (10+35d)
40+40d = 10 + 35d
5d = -30
d = -6
sequence is 2 -4 -10 -16 -22 -28 -34 -40 -46 -52
sum of T1..T5 = -50
sum of T6..T10 = -200
nth term is a+(n-1)d
sum of 1st n terms = n/2(T1+Tn)
a = 2
sum of 1st 5 terms = 5/2 (2 + 2+4d) = 10+10d
6th term = 2+5d
sum of terms 6-10 = 5/2 (2+5d + 2+9d) = 10+35d
10+10d = 1/4 (10+35d)
40+40d = 10 + 35d
5d = -30
d = -6
sequence is 2 -4 -10 -16 -22 -28 -34 -40 -46 -52
sum of T1..T5 = -50
sum of T6..T10 = -200
(copied From above)
20th Term = a +(n-1)d
= 2+19 X -6
= 2 - 114
= -112
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