Question

Sum of first 15 terms of the series 1,3,5, 7............ is​

Answer 1

1+3+5+7+9+11+13+15+17+19+21+23+25+27+29= 225

sum of first n odd no is n^2

Answer 2

Answers:

Required sum is 225.

Step-by-step explanation:

Given series 1,3,5,7,......

First term of this series is 1 and common difference is (3-1)=2

and number of term is 15.

We know

$S = n/2(2a + (n − 1) × d)$

Where

$n =$Number of terms.

$a =$First term of the series

$d =$Common difference

S is sum of n terms.

So, S=15/2[2X1+(15-1)x2]=15/2[2+28]=15/2x30=225

Some others formula of AP series are

an = a + (n – 1) × d

S = n/2[2a + (n − 1) × d

Sum of finite numbers of term= n/2(a + l)