Question

which term of the AP 21, 18, 15 is -81? also is any term 0 ?give reasons for your answer . Pls send the reason don't send the total solution.​

Answer 1

Step-by-step explanation:

a = 21

d = -3

an = -81

n = ?

an = a + (n - 1)d

-81 = 21 + (n - 1)(-3)

-81 -21 = (n - 1)(-3)

-102/-3=(n - 1)

34 = n - 1

n = 35

81 is the 35th term of the AP

2nd part of question

Let 0 be part of the AP

So

a = 21

d = -3

an = 0

n = ?

an = a + (n-1)d

0 = 21 + (n-1)(-3)

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

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

7=n-1

n=8

As n is a whole number 0 is a part of the AP and is the 8th term

Legend-

a=First term

d=Common difference

n=place of term in AP

an=nth term of AP