Question

what is the 21st term of an arithmetic progression whose 11th term is 23and 15th term is 3? Is 40 a term of the series?​

Answer 1

Step-by-step explanation:

11th term =23

a+10d=23 --(1)

15rd term = 3

a+14d =3 --(2)

subtract (1) and(2)

4d = -20

d = -5 and a = 73

so, 21st term of an A.P is

=a + 20d

=73 - 100

= -27