Question

If the sum of n terms is 3n2-4n then find the series

Answer 1

Answer:

It is given that Sum of n terms is 3n2 - 4n

Step-by-step explanation:

Let n be 1 then Sn(sum of n terms) will be :- 3 X (1) square - 4 (1) 3 - 4 = -1 And we know that Sn(sum of n terms) = An(the first term of the A. P) so a1 = -1. S2 = 3 X (2)2 - 4 (2)

= 12 - 8 = 4. To find a2 , we have to subtract S2 and S1, then we get. S2 - S1 = 4 - (-1) = 4 + 1 = 5. To find the difference we have to subtract a2 and a1. so the difference is.

a2 - a1 = 5 - (-1) = 5 +1 = 6. So the following series is :- -1 , 5 , 11 , 17 , 23 , 29 , 35 ..........