Question

Which term of an A.P 21, 18, 15... is -3

Answer 1

Answer:

an=a +(n-1)d

Step-by-step explanation:

a=21, d=a2-a1=-3

an= -3

then put all value into the formula and get the ans.

-3= 21+(n-1)(-3)

-3=21+(-3n)+3

-3=24-3n

3n=27

n=9

-3 is the 9th term