Question

The sum of first n terms of an ap is 4n2+2n find its nth term

Answer 1

here l is the nth term

Answer 2

Answer:

The nth term of the A.P is  8n - 2  

Step-by-step explanation:

Given :  

Sn = 4n² + 2n  …………..(1)

Now , on Replacing n by (n –1) in eq (i),  

S(n – 1) = 4(n – 1)² + 2(n – 1)

nth term of the A.P., an = Sn – S(n – 1)

an = (4n² + 2n) – [4(n – 1)² + 2(n – 1)]

⇒ an =(4n² + 2n) – [4(n² + 1 - 2n) + 2n - 2]

[(a + b)² = a² + b² - 2ab]

⇒ an =(4n² + 2n) – [4n² + 4 - 8n + 2n - 2]

⇒ an =(4n² + 2n) – [4n² - 6n + 2]

⇒ an = 4n² + 2n – 4n² + 6n - 2  

⇒ an =  8n - 2  

Hence, the nth term of the A.P is  8n - 2  

HOPE THIS ANSWER WILL HELP YOU….