Question

Find the number of terms in the A.P 18 ,15 1/2 ,13 ------_47

Answer 1

Answer:

The required answer is 27

Step-by-step explanation:

=> Given :-

A.P.= 18,15½,13,....,-47

Difference = (15½ - 18)= -2½

Lets start from 18 to -47

So,..

First term = a= 18

Last term = l = -47

Difference = d = -2½

Let n be the number of terms ,

So,...

=> l = a +(n-1)d

=> -47 = 18 +(n-1)(-2½)

=> (n-1)2½ = 18+47

=> n-1 = 65/(2½) = 26

=> n = 26 + 1 = 27

Hence the required answer is 27