the sum of n terms is 3n²-4 find the 4th term
Answers
Answered by
1
Step-by-step explanation:
Given: Sn = 3n² - 4n
Replacing n-1 with n
Sn-1 = 3 (n-1) - 4 (n-1)
=3 (n²-2n+1) - 4n + 4
=3n² - 6n +4n +4
= 3n² -10n + 7
Now,
an= Sn -Sn-1
= 3n² - 4n - (3n² - 10n -7)
=3n² - 4n -3n² + 10 -7
= -4n +10-7
3n² and -3n² will be cancelled
= 6n -7
The nth term is 6n-7
Similar questions