[tex]P(x) =-0.002x^2+5x-5000\\P'(x)=-0.004x+5=0\\-0.004x=-5\\x=1250[/tex]
We can deduce that the graph is a negative parabola from -0.002x^2. Therefore, the graph is increasing < 1250 and decreasing > 1250.
P(x) is increasing from [tex][0,1250)[/tex] and decreasing from [tex](1250,\infty][/tex].