Question

Which term of the AP 24, 21, 18, 15, …. is first negative term

Answer 1

Hey there,

Given A. P = 24, 21, 18, 15, ….

First term ( a) = 24

Common difference ( d) = 21 - 24 = -3

The A. P is on a decreasing trend. So, There might be 0 as some term .

Let's see which term of A. P is 0 .

Let the n th term of the A. P = 0

We know that,

$\boxed{ a_{n} = a + ( n - 1 ) d}$

So,

0 = a + ( n - 1 ) d

0 = 24 + ( n - 1 ) -3

-24 = -3n + 3

-27 = -3n

n = 27/3 = 9 .

So, 9th term of the A. P = 0

We know that,
$\boxed{a_{n} = a_{n-1} + d}$

Therefore,

Tenth term = 0 - 3 = -3 .

Thus, The first negative term of the A.P is 10th term

Answer 2

Hope this answer helps you.