Can anyone help me answer these two trigonometry math word problems and show all my work for both?

Question

1. The profit of an organization is calculated by the function P(x) = x² - 4000x + 7800000, where x is the number of units sold. If the net profit is 3800000, find the number of items sold.

Answer 1

Raymond,

              We want to find the value of x that makes P(x) = 3,800,000. So we have 

 

3,800,000=x²-4000x+7,800,000, subtracting 3,800,000 from both sides

 

x²-4000x+4,000,000 = 0 The solution of this quadratic is x=2000 is the number of items sold

 

Jim