Question

the 12th term from the end in the a.p 9,5,1..is -107 . then the numbers of term is a. p. are(a)-151(b)-155(c)-147(d)-159​

Answer 1

Answer:

The last term is -151

option (a) is correct

The number of terms is 41

Step-by-step explanation:

Given A.P is

9, 5, 1...........

Here, a=9 and d=-4

Let the last term be $l$

Also,

12 th term from the end = -107

$T_{12}=-107$

$\implies\:l+11(-d)=-107$

$\implies\:l+11(4)=-107$

$\implies\:l=-107-44$

$\implies\:l=-151$

Number of terms

$=\frac{l-a}{d}+1$

$=\frac{-151-9}{-4}+1$

$=\frac{-160}{-4}+1$

$=40+1$

$=41$