If the sum if n terms of a series is an^2+bn, where a,b are constants, show that it is an A.P.[Arithmetic Progression] Find the the first term and common difference. Also find an AP, whose sum of any number of terms is equal to the square of the number of terms
First part
s1=a(1)^2+b(1) = a+b = t1
s2=a(2)^2+b(2)= 4a+2b = t1+t2
t2= 4a+2b-a-b= 3a-b
therefore d = t2-t1 = 3a-b-a-b = 2a
so first term = a+b
common difference = 2a

Please help me with the second part !!

Question

If the sum if n terms of a series is an^2+bn, where a,b are constants, show that it is an A.P.[Arithmetic Progression] Find the the first term and common difference. Also find an AP, whose sum of any number of terms is equal to the square of the number of terms
First part 
s1=a(1)^2+b(1) = a+b = t1
s2=a(2)^2+b(2)= 4a+2b = t1+t2
t2= 4a+2b-a-b= 3a-b 
therefore d = t2-t1 = 3a-b-a-b = 2a 
so first term = a+b 
common difference = 2a

Please help me with the second part !!

anonymous · Answer

the answer says 2a is the common difference

anonymous · Answer

what is an A.P