Question

5. In an AP. If a = 4 and a 9=20 then the value of d is a)1 b) 2 c) 3 a) d) 4 ​

Answer 1

Answer:

option (b) 2

Step-by-step explanation:

Given :

In an A.P.,

• a = 4
• a₉ = 20

To find :

the value of d

Solution :

Arithmetic Progression :

• It is the sequence of numbers such that the difference between any two successive numbers is constant.  

• General form of AP,

          a , a+d , a+2d , a+3d , . . .

nth term of an A.P. is given by,

$\longmapsto \bf a_n=a+(n-1)d$

where

a denotes the first term

d denotes the common difference

9th term = 20

a + (9 - 1)d = 20

4 + 8d = 20

8d = 20 - 4

8d = 16

  d = 16/8

  d = 2

Hence, common difference, d = 2

Answer 2

»» option (b) 2 »»

Step-by-step explanation:

Given :

In an A.P.,

a = 4

a₉ = 20

To find :

the value of d

Solution :

Arithmetic Progression :

It is the sequence of numbers such that the difference between any two successive numbers is constant.

General form of AP,

a , a+d , a+2d , a+3d , . . .

nth term of an A.P. is given by,

an = a+(n-1)d

where

a denotes the first term

d denotes the common difference

9th term = 20

a + (9 - 1)d = 20

4 + 8d = 20

8d = 20 - 4

8d = 16

d = 16/8

d = 2

• common difference, d = 2