Question

Find value of a8-a4 if ap is 4,9,14....
Plz ans

Answer 1

Ans : a8 - a4
= (a+7d) - (a+3d)
=4d
=4×5
=20

Value of a8 - a4 = 20

Answer 2

The value of $a_8-a_4$ is 20.

Step-by-step explanation:

We are given the following sequence of an A.P. below;

4, 9, 14, 19,......

As we know that the nth term of an A.P. is given by the following formula;

$a_n=a+(n-1)d$  

Here, a = first term of an AP = 4

          d = common difference = Second term - First term = 9 - 4 = 5

So, the 8th term of an AP is given by;

$a_8=4+(8-1)d$

$a_8=4+(7 \times 5)$

$a_8=4+35 = 39$

Similarly, the 4th term of an AP is given by;

$a_4=4+(4-1)d$

$a_4=4+(3 \times 5)$

$a_4=4+15 = 19$

Now, the value of $a_8-a_4$ = 39 - 19 = 20.