Which expressions are polynomials

a. -7x^2 + 5/3x
b. 6x^2 + 5x
c. x^2 + 5x^1/5
d. -x^2 + 5x

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?

Two angles are complementary. the large angle is 36 more than the smaller angle. what is the measure of the large angle?

The number of fish in a lake can be modeled by the exponential regression equation y=14.08 x 2.08^x where x represents the year