Question

The sum of the first ten terms of an A.P is three times the sum of the first five terms, then find ratio of the first term to the common difference. 

Answer 1

We know that, 

According to given condition, 

Answer 2

Let the 1st term be a and common difference be d

Then by the problem

10/2(2×a+(10-1)×d)=3×5/2(2×a+(5-1)×d

=>2(2a+9d)=3×(2a+4d)

=>2a+9d=3a+6d

=>a=3d

=>a:d=3:1