Question

If sum of n terms of an AP is n²+8n, then find the common difference of the AP

Answer 1

if n=1

sum=1+8=9=a1

if n=2

sum=1*2^2+8*2=20

s2-s1=a2=11

therefore, d=a2-a1=11-9=2

Answer 2

I hope this will help you..