Question

Which term in a.p,18,15,12,.....is equal to zero​

Answer 1

a= 18
d= -3
an=0
a+(n-1)d=0
18 + (n -1)-3=0
18 - 3n +3 =0
-3n = -15
n= 5



Hope it helps!!

Answer 2

Given : The AP is 18 , 15 , 12 , . . . .

To find : The term which is equal to zero

Concept to be implemented :

If in an arithmetic progression

First term = a

Common difference = d

Then nth term of the AP

= a + ( n - 1 )d

Solution :

Let the given AP is 18 , 15 , 12 , . . . .

First term = a = 18

Common Difference = d = 15 - 18 = - 3

Let nth term of the AP = 0

So by the given condition

$\displaystyle \sf{ a + ( n - 1 )d = 0}$

$\displaystyle \sf{ \implies 18 - 3 ( n - 1 ) = 0}$

$\displaystyle \sf{ \implies - 3 ( n - 1 ) = - 18}$

$\displaystyle \sf{ \implies ( n - 1 ) = 6}$

$\displaystyle \sf{ \implies n = 7}$

Conclusion : 7th term of the AP is zero

━━━━━━━━━━━━━━━━

Learn more from Brainly :-

$1.$ If for an A.P., S15= 147 and s14=123 find t 15

(A) 24 (B) 23 (C) 47 (D) 46

https://brainly.in/question/34324030

2. Insert there arithmetic means between -20 and 4

https://brainly.in/question/29887163