algebra
posted by lisa on .
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
ticket sales peak
number of tickets sold

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
(x13)^2 = 1.6666 N + 189
(x13)^2 = 1.6666 (N  113.4)
13 days and 113 tickets 
If you know calculus
dN/dx = 0 at max = 1.2 x + 15.6
1.2 x = 15.6
x = 13