Question

Find the 84th term of the arithmetic sequence 18, 31, 44, ...

Answer 1

1097

Explanation:

Common Difference:

d=a_2-a_1=(31)-(18)=13

d=a

2

​ −a

1

​ =(31)−(18)=13

a_n=a_1+(n-1)d

a

n

​ =a

1

​ +(n−1)d

\text{84th term:}

84th term:

a_{84}=18 + (84-1)(13)

a

84

​ =18+(84−1)(13)

a_{84}=18 + (83)(13)

a

84

=18+(83)(13) a_{84}=1097 a 84

​ =1097

Answer 2

common difference = 31-18

common difference =13

from,

An=A1 +(n-1)d

A84=18+(84-1)13

A84=1097