Show work for this equation

What kinds of numbers have an odd number of factors?

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?

Is the square root of 4 plus the square root of 16 rational?