Question

Write the common difference of an A.P. whose nth term is an= 3n + 7.

Answer 1

Given:
an = 3n + 7…………(1)

Put n = 1 in eq 1
a1 = 3×1 +7
a1 = 3 +7
a1 = 10

Put n= 2 in eq 1
a2=  3×2+7
a2 = 6 +7
a2 = 13

Put n = 3 in eq 1
a3 = 3×3 +7
a3= 9 +7
a3 = 16

First three terms of an  AP are= 10, 13, 16

Common difference (d) = a2 - a1 or a3 - a2
d =  a2 - a1= 13 -10
d = 3

Hence,  the common difference of an AP is 3.

HOPE THIS WILL HELP YOU..

Answer 2

Hey..!!

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a1 = 3(1) +5
     =3+5 =8
a2= 3(2)+5
    =6+5 =11

a2-a1 =11-8 =3
d=3Ans.

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I Hope It's help you.