Question

If sum of n terms is 3n^2-4n .then find the nth term​

Answer 1

Answer:

nth term = 6n - 7

Step-by-step explanation:

3n^2 - 4n

$sn = 3 {n}^{2} - 4n \\ s1 = 3 {(1)}^{2} - 4(1) \\ = 3 - 4 \\ = - 1 \\ s2 = 3 {(2)}^{2} - 4(2) \\ = 12 - 8 \\ = 4 \\ s3 = 3 {(3)}^{2} - 4(3) \\ = 27 - 12 \\ = 15$

s1 = a1 = -1

s2 = a1 + a2 = 4

= -1 + a2 = 4

a2 = 4 + 1

a2 = 5

s3 = a1 + a2 + a3 = 15

- 1 + 5 + a3 = 15

a3 = 15 - 4

a3 = 11

-1, 5, 11

a = -1 d = 6

an = a + (n-1)d

= -1 + (n-1)6

= - 1 + 6n - 6

= 6n - 7

therefore the nth term = 6n - 7

hope you get your answer