Question

Find the sum of the first 30 terms of the sequence. a_(n)=4n+1

Answer 1

We know that
a(n)=4n+1
To find the sum of the first n terms of an arithmetic series
use the formula
Sn=n(a1 + an)/2
a1--------------> is the first term
an--------------> is the last term
n--------------- > is the number of terms
we have that
a1------------> 4*(1)+1=5
a30----------> 4*(30)+1=121
n------------- > 30
S30=30*(5 + 121)/2=1890

the answer is 1890