Question

the 3rd term of an arithmetic sequence is 9 and 10th term is 23 write its 20th term​

Answer 1

Answer:

3rd term = a+2d = 9 -----1.

10th term = a+9d = 23 ----2.

Subtracting 1 from 2 :

 a + 9d = 23

 a + 2d =  9

-     -         -      

        7d = 14

  ==> d = 14/7 = 2

Put value of d in 1.

a+2X2 = 9

a = 9 - 4

a = 5

20th term = a+19d = 5 + 19X2

                               = 5 + 38 = 43

Step-by-step explanation:

Hope it helps you buddy :)