Question

If in an AP, a=15 , d= -3 and an = 0 , then find the value of n.

Answer 1

Answer:

an = a+(n-1)d

0 =15+(n -1)-3

0-15=-3n +3

-15-3=-3n

-18=-3n

n=-18/-3

n=6

Answer 2

Answer:

n = 6

Step-by-step explanation:

Given:-

a = 15

d = -3

Tn = 0

To find:-

value of n

Sol

Tn = a+(n-1)d

Substituting the given values, we get

0 = 15+(n-1)-3

0 = 15+(-3n+3)

0 = 18-3n

3n = 18

n = 6