What is the sum of the first 30 odd numbers?
900
Every term is of the form 2n + 1, i.e. the sequence is 1,3,5,…
First term, a = 1
Common difference, d = 2
Then the 30th odd term will be:
⇒T30=a+(n−1)d=1+(30−1)2=59
⇒Sum of n terms=n2(a+l) , where l=T30
⇒Sum of n terms=302(1+59)
⇒Sum to 30 terms=15×60=900