Question

if the sum of n terms of AP is 4n-n² what is the sum of first 2 terms

Answer 1

Sn=4n-n2

first 2 terms=

n=2

4x2-2x2=8-4=4

Answer 2

First take n=1 then

4n-n^2 = 3 = a1

Now take n=2 then

a2 = 4

Sum of first two terms = 3+4 = 7