Question

Find the sum of all odd numbers from 351 to 393

Answer 1

Answer:

8184

Step-by-step explanation:

AP:351,353,355...393

a=351

d=353-351=2

let an be the last term of an ap

an=a+(n-1)d=351+(n-1)d

393-351=(n-1)d

42=(n-1)2

21=n-1

n=22  .............(i)

sum=n/2(2a+(n-1)d)

       =22/2(702+(21)(2))  ........from(i)

       =11(744)

       =8184