Question

Without adding, find the sum 1+3+5+7+9+11+13+15+17+19+21?​

Answer 1

Answer:

121

Step-by-step explanation:

this is a very easy ques it might have tricked you since it is in A.P . If you are in class 10 you would know this as it is a part of class 10 maths but if not try these ques ...it will increase your interest towards maths ...

solution-  formula of Sn =n/2 { 2A + (n-1 )d}

                                  S11 =11/2 ( 2* 1 + 10* 2)

                                   S11= 11/2 (2+20)

                                S11 =11/2 *22      

                                S11=11*11= 121                          

n= no. of terms

A = first term

Sn = sum of terms

hope this helps ....