Question

A company's monthly profit, P, from a product is given by P = −x2 + 105x − 1050, where x is the price of the product in dollars. What is the lowest price of the product, in dollars, that gives a monthly profit of $1,550?

Answer 1

1550 = -x^2 + 105x -1050
How do i find the roots for x= 40 and 65 ??