The profit, in dollars, that a school will earn from selling tickets to a dance can be modeled by the function p(x)= -25x2 + 400x where x is the price, in dollars, of each ticket. What is the price per ticket for which the
school will earn its maximum profit?
A.
$8
B. $16
C. $25
D. $400

solution:

the given function is ,

      =

the three roots of this quadratic function is , 0 ,8 and 10.all the roots are real and rational.

if a quadratic equation is of the form ,

sum of the roots = a + b +c= 0+8+10=18=  

product of roots taken two at a time = a b + b c+ c a = 0+80+0=80 =  

product of roots = a b c = 0=  

there are 11 doors in a hall starting from 0 to 11.the entry in the hall is permitted through gate number 0 and exit is allowed through only gate number 8 and 10.so, three roots(0,8,10) of quadratic function is given by entry and exit route of this hall.

but there’s no any figure there!