Question

1+3+5+.....+11=..........​

Answer 1

Step-by-step explanation:

here a=1

d=2

l=11

l=a+(n-1)d

11=1+(n-1)2

11-1=(n-1)2

10/2=(n-1)

5+1=n

6=n

S6=n/2(a+l)

S6 = 3(1+11)

S6= 3*12

S6= 36