Question

1. If the sum of the first n terms of an AP is 4n-n, what is the first term (that is $)? What is the sum of first two terms? What is the second term? Similarly, find the 3rd, the 10th and
the nth terms.​

Answer 1

Step-by-step explanation:

here, sum of first n terms, s(n) = 4n-n = 3n

we know that,

sum of n terms = (n/2)*(1st term + nth term)

then, 3n = (n/2)*(a+l)

a+l=6. (l= nth term)

and first term, a = 6 - nth term

sum of first 2 terms = first term*2 + common diff.

= 2a + d

second term = a + d

3rd term = a + 2d

10th term = a + 9d

nth term = a + (n-1)d = 6 - a ( from above calculations)