Question

which term of an ap 21 18 15 ........is -18

Answer 1

Answer:

Step-by-step explanation:

a=21

d= -3

an=a=(n-1)d

-18=21+(n-1)-3

-39=(n-1)-3

(n-1)=13

n=14

Answer 2

Answer:

14th term

• Step-by-step explanation:

Given AP is 21,18,15,.........,-18

a=21, d=18-21

           = -3

an=-18

an=a+(n-1)d

= -18=21=(n-1)*-3

= -18-21=(n-1)*-3

=-39=(n-1)*-3

= -39/-3=(n-1)

=13=n-1

=13+1=n

=14=n.

∴ The 14th term of the given AP: 21,18,15,..... is -18