Question

if sn = 5n^2-3 find the first term of ap​

Answer 1

Let a  

n

​

 be the n  

th

 term of the A.P.  

Then, a  

n

​

=S  

n

​

−S  

n−1

​

 

⟹a  

n

​

=(5n  

2

+3n)−{5(n−1)  

2

+3(n−1)}          

togetS  

n−1

​

=5(n−1)  

2

+3(n−1)]

a  

n

​

=(5n  

2

+3n)−(5n  

2

−7n+2)

⟹a  

n

​

=10n−2

Mark as brain list :')