Question

withouth ading find the sum of
1+3+5+ 7+9 +11+ 13 + 15+ 17+19+21​

Answer 1

Step-by-step explanation:

1+3+5+7+9+11+13+15+17+19=?

We have to find it using Arithmetic Progression.

a=1

d=2

tn=19

a+(n-1)d=19

1+(n-1)2=19

(n-1)2=19-1

(n-1)2=18

n-1=18/2

n-1=9

n=9+1

n=10

Sn=n[2a+(n-1)d]/2

Sn=10(2(1)+(10-1)2)/2

Sn=10(2+9(2))/2

Sn=10(2+18)/2

Sn=10(20)/2

Sn=200/2

Sn=100

Sum of the given numbers is 100.

hope it helps

Answer 2

Answer:

1+3+5+7+9+11+13+15+17+19+21=

121

hope it use ful for you

thankyou