Question

if sum of the first n term is 4n-n^2 what is the first term. what is the sum of first two terms. what is second term. similarly find the 3rd, 10th and nth term​

Answer 1

Answer:

Sn = 4n - n^2

S1 = a1= 4(1)-1^2

a1= 4-1=3

s2 = sum of fst two terms = 4(2)- 2^2

s2= 4

s2= a1+a2

4=3+a2

1=a2

d=a2-a1=1-3= -2

an = a+ (n-1)d = 3+(n-1)(-2)  = 3-2n+2=5-2n

a3 = 3 + (3-1)(-2) = 3-8= -5

a10= 3+(-18) = -15

Step-by-step explanation: