Question

Find the 20th and 25th terms of AP :3,8,13,18.......?

Answer 1

20 is the 20th term of Ap

Answer 2

The 20th term is 98 and the 25th term is 123.

Step-by-step explanation:

Given:

The series 3,8,13,18,........... is in A.P.

To find:

20th & 25th terms of the A.P.

Solution:

The terms of A.P. are 3,8,13,18.......

first term= a= 3

difference between the terms= d= 8-3= 5

The formula to find the terms is

$t_{n}$$= a+(n-1)d$

To find the 20th term, n=20, a=3, d=5

∴ $t_{20}$= 3+(20-1)5

∴ $t_{20}$= 3+(19)5

∴ $t_{20}$= 3+95

∴ $t_{20}$= 98

Simlarly, for the 25th term, n=25, a=3, d=5

∴ $t_{25}$= 3+(25-1)5

∴ $t_{25}$= 3+24(5)

∴ $t_{25}$= 3+120

∴ $t_{25}$= 123

Thus, the 20th & 25th terms of the given A.P. are 98 and 123 respectively.

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