What is 453,605 rounded to the nearest thousand

Which approach to the theory-and-research cycle does the following sequence reflect: (1) specific observations suggest generalizations, (2) generalizations produce a tentative theory, (3) the theory is tested through the formation of hypotheses, and (4) hypotheses may provide suggestions for additional observations?

Which expression is equivalent to the expression shown?

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?