2. The profit P (in thousands of dollars) for an educational publisher can be modeled by P=-b3 + 5b2+ b where b
is the number of workbooks printed (in thousands).
Currently, the publisher prints 5000 workbooks and
makes a profit of $5000. What lesser number of workbooks
could the publisher print and still yield the same profit

i pretty sure it is

ab will be equal to

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.