Check whethet a,a+70,a+140,a+210,..where a=(77)^77 form an A.P or not. If yes, find the first term and common difference.

Dear Student, 

a , a+70 , a+140 , a+210 ............. 
to check whether this series is AP or not , we will have to check if the common difference is same 
common difference = an+1 - an
if n = 1 then, d = a + 70 - a = 70 [ a2 - a]
if n = 2 then, d = a +140 - (a +70) = a +140 - a - 70 = 70  [ a3 - a2]
Common difference is same so this series is AP

So, the common difference = 70

​​​​

And first term of the AP is (a) which is given,  a = 7777

Regards                                    
 

  • 0
What are you looking for?