Question

How many terms are there in the AP 18,15½,13,...,-47?​

Answer 1

Hello dear here is your answer.

The given sequence is an AP.

So,,

first term of an ap is=a =18

common deference =d =15 1/2-18

last term of an ap = $a_n=-47$

you have to use this formula

$a_n=a+(n-1)d$

Then you have to find n

so, you will get your answer.

Answer 2

Answer:

There are 27 terms in the AP 18,15½,13,...,-47.

Step-by-step explanation:

AP = a1 ,a2 , a3.......an

AP = 18,15½,13,...,-47

AP = 18 , 15.5 , 13 .........-47

1/2 = 0.5

a = 18

an = -47

d = a2 - a1

d = 15.5 - 18

d = -2.5

an = a + (n - 1) d

=> -47 = 18 + (n - 1) -2.5

=> -47 - 18 = (n - 1) -2.5

=> -65 = (n - 1) -2.5

=> -65/-2.5 = (n - 1)

=> 26 = n - 1

=> 26 + 1 = n

=> n = 27

Therefore there are 27 terms in the AP 18,15½,13,...,-47.

Hope it helps you.

Thanks