Question

If the 3rd term and the 9th term of an AP are 4 and -8 respectively, which term of this AP is zero

Quality answer required.Wrong answer will be reported​

Answer 1

Answer:

Zero is the 5th term of the AP

PLEASE REFER THE ATTACHMENT

Answer 2

Answer:

5th term of the A.P is zero .

Step-by-step explanation:

Given , the third term of the AP is 4 and ninth term of the AP is -8

nth term of a series in AP is

Tn = a+(n-1)d

where

a is first term and

d is the common difference .

so , third term of AP :

T3 = a+(3-1)d=4

a + 2d = 4 ........... eq (1)

and ninth term of AP :

T4 = a+(9-1)d= -8

a + 8d = -8 .......... eq(2)

eq(2)-eq(1) :

(a+8d) - ( a + 2d ) = -8-4

6d=-12

d=-2

substitute the value of d in equation (1) , we get the value of "a"

a+2d=4

a+2(-2)=4

a=8

let an nth term in the AP be equal to zero , substitute values of "a" and "d"

a+(n-1)d=0

8+(n-1)(-2)=0

-2n+2=-8

-2n=-10

n=5

therefore 5th term of the AP is zero