Question

Find the sum of the first 20 terms of the A.P. 1,3,5,7...

Answer 1

Answer:

9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47

Answer 2

Answer:

400

Step-by-step explanation:

we have a=1,d=2,n=20

hence, sum of first 20 terms are:

Sn=$\frac{n}{2} [2a+(n-1)d]$

⇒$\\ \frac{20}{2} [2*1+(20-1)2]$

⇒$\\ 10[2+38]=400$