Question

5. (ii) Find the number of terms in the A.P: 18, 15.5, 13,......., - 47.

Urgent pls anyone pls fast ​

Answer 1

Answer:

number of terms = 25

Step-by-step explanation:

given : a = 18, d = 15.5 - 18 = -2.5, L = Tn = -47

to find number of terms n

formula used Tn = a + (n-1)d

- 47 = 18 + (n -1) × -2.5

-47 = 18 - 2.5 n + 2.5

=> - 47 - 18 - 2.5 = -2.5 n

=> -67.5 = - 2.5 n

=> n = -67.5/-2.5

=> n = 25