Question

find the no.of terms of Ap 17, 14.5, 12 .......-38

Answer 1

Here, a=17; d=-2.5; tn=-38

tn = a+(n-1)d

-38 = 17+(n-1)-2.5

-55 = (n-1)(-2.5)

-55/-2.5 = n-1

23 = n-1

n = 23

Hence, there are 32 terms in the A.P.

Answer 2

Answer:

No. of term = 23

Step-by-step explanation:

In an A.P,

First term, a = 17

Common difference, d = - 2.5

Last term = -38 = an

Apply formula of A.P

an = a + (n - 1) * d

-38 = 17 +  (n - 1) * (- 2.5)

-38 - 17 =  (n - 1) * (- 2.5)

- 55/ - 2.5 =  (n - 1)

22 = n - 1

22 + 1 = n

n = 23

No. of term = 23