Question

If the second term of an ap is 8 and the 5th term is 17 find its 19th term

Answer 1

Answer:

Step-by-step explanation:

a2 =8

a5=17

a19=?

a+d=8         (1)

a+4d=17.    (2)

From 1 and 2

a+4d - a -d = 17-8

3d=9

d=9/3

=3

Substitute d=3 in (1)

a=8-3

=5

So,   a19= a+ 18d

            =5+ 3*18

            = 5+ 54

            =  59

Answer 2

Concept

Arithmetic progression is that particular series in which there is common difference between terms.

Given

Second term of an ap is 8 and the 5th term is 17

Find

We are asked to find the 19th term

Solution

Second term of an ap is 8

$a+d=8.....(1)$

Fifth term is 17

$a+4d=17.....(2)$

Subtract 1st equation from 2nd equation.

we get,

$a+4d-a-d=17-8\\3d=9\\d=3$

We will put the value of d=3 in 1st equation

$a+d=8\\a+3=8\\a=5$

Now we will find the 19th term

$a+18d\\5+18(3)\\5+54\\59$

Hence 19th term is 59