Question

Find the sum of 1+3+5...........+55​

Answer 1

Step-by-step explanation:

hope this is you.......

Answer 2

a=1, d=3-1,An=l=55

d=2

An=a+(n-1)d

55=1+(n-1)2

55=1+2n-2

55=-1+2n

-2n=-55-1

-2n=-56(–×―=+)

n=56÷2

n=28

Sn=n÷2(a+l)

Sn=28÷2(1+55)

Sn=28(56)/2

Sn=28×28

Sn=784