Question

1. If the 9th and 21st terms of an A.P. are 75 and 183
respectively, find its 81st term.
(HOTS)​

Answer 1

Answer:

Answer:

723

Step-by-step explanation:

9th term = a + 8d = 75

21st term = a+20d = 183

                       -12d = -108

                     =>   d = 108/12

                     => d = 9

we have a+8d = 75

          =>  a + 8(9) = 75

          =>       a = 75-72

          =>       a = 3

so, 81st term = a+80d

                      = 3 +  80(9)

                      = 3 + 720

                      = 723