Practice Determine whether each function is continuous at the given x-value. Justity your answer using the continuity test. 12. y= 13 - 4x =1 13. y= x- 2:* =2 14. /(x) = *+3 (x - 3)2;*= -3 15. y = xx = 3 16. f(x) = 3x + 5ifx s -4 [-x+ 2ifx > -4ix=-4 17. /(x) = 2x + lifx21. 4-xifx+ 2+ x-1 21.y=8-x3- 24 22. A(x) = x10 - x + 5x8 23. g(x) = (x - 3)2 -1/ 24. y = = 25. K(x) = -3+ 2 Graphing Graph each function. Determine the interval(s] for which the function is Calculator increasing and the interval(s) for which the function is decreasing. 26. y = x3+ 3x2 - 9x 27. y= -x - 2x + 1 28. A(x) = - 1 29. g(x) = * + 5 x +1 x - 2 30. y = x2-41 31. y = (2 x- 3)2+ 1 Applications 32. Physics The gravitational potential energy of an object is given by U(r) = GmMe and Problem where G is Newton's gravitational constant, m is the mass of the object, M is Solving the mass of Earth, and r is the distance from the object to the center of Earth. What happens to the gravitational potential energy of the object as it is moved farther and farther away from Earth? 33. Critical Thinking A function /(x) is increasing when 0 2. The function has a jump discontinuity when x = 3 and f(x) - - as X 60. a. If f(x) is an even function, then describe the behavior of f(x) for x