Question

the sum of n terms of an ap is n(5n-3). find the ap.

Answer 1

Heya user !!!

Here's the answer you are looking for

The sum of n terms or Sn = n (5n - 3)

So S1 = 1(5-3) = 2

Sum of one term means the first term itself that is a1

So a1 is 2

Now S2 = 2(10-3) = 14

S2 means sum of first 2 terms

So a1 + a2 = 14

a2 = 14 - a1 = 14 - 2 =12

a2 = 12

Also,
a2 = a1 + d

12 = 2 + d

d = 10

Thus the AP is 2, 12, 22, 32.....


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Answer 2

Sn=n(5n-3)=5n^2-3n

5(1)^2-3(1)=1/2(2a+0d)
(5-3)2=2a

2*2=2a
a=2

d=10

2,12,22.......ap