What are the solutions of 3x^2+ 15 = -6x

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?

Choose the more precise measurement. 26.4 cm or 8.39 cm

This is about circle theorems. someone asap : (