Does one diagonal always the perpendicular bisector of the other

You can model the population of a certain city between 1955-2000 by the radical function p(x)=55,000 sqrt x-1945. using this model, in which year was the population of that city 220,000

15 point ! ~ see if you know the answer to both you!

Use the function f(x) is graphed below. the graph of the function to find, f(6). -2 -1 1 2