Question

18. Find the 21st term if a₁ = 3/5 and
d = -1/3

(a) -6.07
(b) 11.67​

Answer 1

a

Explanation:

the nth term of an arithmetic sequence is

`a_{n` a₁ + (n - 1)d

here a₁ =
`(3)/(5)` and d = -
`(1)/(3)` , then

a₂₁ =
`(3)/(5)` + (20 × -
`(1)/(3)` )

=
`(3)/(5)` -
`(20)/(3)`

= 0.6 - 6.67

= - 6.07 ( to 2 decimal places )