N(x)=-0.6^2+15.6x+12, where x is the number of days since the concert was first announced, When will daily ticket sales peak and how many tickets will be sold that day

Question

ticket sales peak-
number of tickets sold-

Answer 1

assume you mean:

N(x)= -0.6 x^2 + 15.6 x + 12

+0.6 x^2 - 15.6 x = -N + 12

x^2 - 26 x = -1.6666 N + 20

x^2 - 26 x + 169 = -1.6666 N + 189

(x-13)^2 = -1.6666 N + 189

(x-13)^2 = -1.6666 (N - 113.4)
13 days and 113 tickets

Answer 2

If you know calculus
dN/dx = 0 at max = -1.2 x + 15.6
1.2 x = 15.6
x = 13