Can someone pleaseee help me??

What signals you that factoring by grouping is the best method to use when factoring a problem?

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?

Write 17/20 as a decimal and as a percent.