Which equation is an identity?

3(x - 1) = x + 2(x + 1) + 1

x-4x + 1) = -3(x + 1) + 1

2x+3 = 2(4x + 2) + 2

(6x – 3) = 3(x + 1) - x-2

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?

Acylinder has volume 45π and radius 3. what is it’s height?

Which statement shows that 6.24 is a rational number? a. 6.24 = 6.242424 b. 6.24 = 6.24 c. 6.24 = 68⁄33 d. 6.24 = 66⁄25