For what value of n will 416−5nachieve maximum value if nϵN.
3
416−5n gets maximum value if 16-5n is least
As n ∈ N, for n = 1 16 - 5n = 11
n = 2 16 - 5n = 6
n = 3 16 - 5n = 1
n = 4 16 - 5n = -4
. .
. .
. .
. .
The sequence is 411, 46, 41, 4−4, -----------
Observe that after n = 3, all the terms are negative and maximum value among positive terms occurs
for n = 3.
So, given expression 416−5n achieves maximum value for n = 3.