Question

whats the ninth term of 25 20 15 10 5

Answer 1

Given:

The sequence is 25, 20, 15, 10, 5.

To find:

The ninth term of the given sequence.

Solution:

We have,

25, 20, 15, 10, 5

It is an AP because the difference between two consecutive terms are same.

Here,

First term (a) = 25

Common difference (d) = 20-25

                                       = -5

The nth terms of an AP is

$a_n=a+(n-1)d$

Where, a is the first term and d is the common difference.

Putting a=25, n=9 and d=-5 to get the 9th term.

$a_9=25+(9-1)(-5)$

$a_9=25+(8)(-5)$

$a_9=25-40$

$a_9=-15$

Therefore, the ninth term of the given sequence is -15.