Question

If 4 and 7 are the 2nd and 3rd terms of an A.P. respectively, then its first term is _______.

Answer 1

Answer:

the first term is 1

Step-by-step explanation:

let the first term be a and d be the common difference

a + d = 4 and

a + 2d = 7

on solving the 2 equations

a + d = 4

a + 2d = 7

---------------

-d = - 3

d = 3

putthing d= 3 in a + d = 4 we get

a + 3 = 4

a = 1

Answer 2

Given : 4 and 7 are 2nd and 3rd term of an A.P

To find : first term

Solution:

an AP series is of a  form

a  , a + d ,  a + 2d , ........................................ , (a + (n-1)d)

a = first term

d = = common difference

nth term = a + (n-1)d

2nd term = a  + d   = 4        

3rd term = a + 2d  = 7        

2 * Eq1 -   Eq2

=> 2a + 2d  - a - 2d  =  8  - 7

=> a = 1

First term is  1

Additional info

d = 3

AP is  1 , 4  , 7 , 10  ,........

Learn more:

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