Question

Which term of AP 81, 78,75... is zero.​

Answer 1

Answer:

For n=55 it becomes zero.

Used formula: an=2a+(n-1)d

Answer 2

Answer:

28th term of the given A.P is zero

Step-by-step explanation:

In the given A.P,

First term, a=81

Common difference, d=second term-first term

=78-81

So, d= -3

We know that nth term of an A.P,an=a+(n-1)d--------(1)

n is the number of terms.

Here, according to the question, an=0.

substituting all these values in (1),

equation becomes,

0=81+(n-1)(-3)

n is our required answer. so, solving,

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

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

27=(n-1)

n-1=27,

n=28

So, 28th term of the given A.P is zero.

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