Question

sum of n terms is 12 and sum of n term is 9​

Answer 1

Answer:

The sum of n terms of AP is the sum(addition) of first n terms of the arithmetic sequence. It is equal to n divided by 2 times the sum of twice the first term – 'a' and the product of the difference between second and first term-'d' also know as common difference, and (n-1), where n is numbers of terms to be added.

Answer 2

Answer:

Question is incomplete

Step-by-step explanation:

Sum of n terms is 12

Nth term is 9

.: 9 = a+(n-1)d

.: 12 =n/2(a+9)

.: 24 = an + 9n