Question

The 55th term of the arithmetic sequence 11, 21, 31, ...11,21,31,

Answer 1

t1=11,t2=21,t3=31

d=10

55/3= 18 .3

55th term is 11

Answer 2

Given

We have given

a=11

A2= 21

and common difference is given which is 21-11=10

To Find

55th term of the arithmetic sequence

$\sf\huge\bold{\underline{\underline{{Solution}}}}$

We have first term (a) =11

second term (a₂)=21

common difference (d)= a₂-a₁=21-11=10

to find nth term we will use formula:

an=a+(n-1)d

=>an=11+(55-1)10

=>an=11+54×10

=>an=11+540

=>an=551

Therefore, 55th term of the arithmetic sequence is 551

Extra information=>

when we have to find nth term from last of an arithmetic sequence:

=>n/2(a+l) where ,l is the last term.

Sum formula for Arithmetic sequence

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