For an A.P if t1= 100, tn= 1000 and n=10 find
Sn.
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Answer:
a = 100
an term = 1000
n = 10
an term = a + (n-1) d
1000 = 100 + 9d
d = 100
Sn = n/2 ( 2a + (n-1)d)
Sn = 10/2 ( 2× 100 + 9 × 100)
Sn = 5 ( 200 +900)
Sn = 5 ( 1100)
Sn = 5500
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