Answers

2016-07-30T11:07:55+08:00
Apply the formula for the sum of arithmetic sequence..

Sn = n/2 [2a1 + (n-1)d]

100 = n ( number of terms)
a1 = 1
d = 2 (common difference) a2-a1 = d

How the sequence looks like..

1,3,5,7,..., up to the 100^th term

substitute the given in the formula given.

Sn = 100/2 [ 2(1) + (100-1) 2]

Sn = 50 [2 + (99)2]

Sn = 50 [2 + 198]

Sn = 50 [200] (multiply)

Sn = 10000

10000 is the sum of the first 100 odd numbers.
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