The price of a certain monthly magazine is x dollars per copy. The total profit from the sales of the magazine is P dollars. It is given that P=Y+Z, where Y varies directly as x and Z varies directly as the square of x. When x is 20, P is 80000; when x is 35, P is 87500.
(a) Express P in terms of x.
==P=6000x-100x^(2)
(b) Find the profit when x=15.
==67500
(c) Using the method of completing the square, express P in the form a-b(x-c)^(2), where a,b and c are constants. Find the values of a,b and c.
==???
(d) Hence, or otherwise, find the value of x when P is maximum.
==???

Question

The price of a certain monthly magazine is x dollars per copy. The total profit from the sales of the magazine is P dollars. It is given that P=Y+Z, where Y varies directly as x and Z varies directly as the square of x. When x is 20, P is 80000; when x is 35, P is 87500.
(a) Express P in terms of x.
==>P=6000x-100x^(2)
(b) Find the profit when x=15.
==>67500
(c) Using the method of completing the square, express P in the form a-b(x-c)^(2), where a,b and c are constants. Find the values of a,b and c.
==>???
(d) Hence, or otherwise, find the value of x when P is maximum.
==>???

anonymous · Answer

hi! i'm too busy but why don't you check out the math forum? if no one answers your question there in the first 10 minutes, you can just pm someone from the list to ask for help. have a nice day!