Q. 174.8( 5 Votes )

Thesumsof an terms of two arithmetic progressions are in the ratio (7n – 5) : (5n + 17). Show that their 6th terms are equal.

Answer :

Wrong question. It will be 7n + 5 instead of 7n – 5.


Given: Ratio of sum of n terms of 2 AP’s


To Prove: 6th terms of both AP’S are equal


Let us consider 2 AP series AP1 and AP2.


Putting n = 1, 2, 3… we get AP1 as 12,19,26… and AP2 as 22,27,32….


So, a1 = 12, d1 = 7 and a2 = 22, d2 = 5


For AP1


S6 = 12 + (6 - 1)7 = 47


For AP2


S6 = 22 + (6 - 1)5 = 47


Therefore their 6th terms are equal.


Hence proved.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Geometric Progression58 mins
General Term of Miscellaneous progression46 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses