IF the sum of first p terms of an AP is (ap2+bp), find its common difference.
Given that the sum of p terms of an AP is (ap2+bp).
Now, Put p = 1,2,3,......
S1=a(1)2+b(1)S1=a+b=a1S2=a(2)2+b(2)S2=4a+2bNow, S2=a1+a24a+2b=a+b+a24a+2b−a−b=a23a+b=a2Common difference, d=a2−a1d=3a+b−(a+b)d=3a+b−a−bd=2a
Therefore, the common difference of the given AP is 2a.