Problem Set 71: Finding Limits: Properties of Limits

1. Give an example of a type of function f whose limit, as x approaches a, is f(a).

2. When direct substitution is used to evaluate the limit of a rational function as x approaches a and the result is f(a)=00, does this mean that the limit of f does not exist?

3. What does it mean to say the limit of f(x), as x approaches c, is undefined?

For the following exercises, evaluate the limits algebraically.

4. limx0(3)

5. limx2(5xx21)

6. limx2(x25x+6x+2)

7. limx3(x29x3)

8. limx1(x22x3x+1)

9. limx32(6x217x+122x3)

10. limx72(8x2+18x352x+7)

11. limx3(x29x5x+6)

12. limx3(7x421x312x4+108x2)

13. limx3(x2+2x3x3)

14. limh0((3+h)327h)

15. limh0((2h)38h)

16. limh0((h+3)29h)

17. limh0(5h5h)

18. limx0(3x3x)

19. limx9(x2813x)

20. limx1(xx21x)

21. limx0(x1+2x1)

22. limx12(x2142x1)

23. limx4(x364x216)

24. limx2(|x2|x2)

25. limx2+(|x2|x2)

26. limx2(|x2|x2)

27. limx4(|x4|4x)

28. limx4+(|x4|4x)

29. limx4(|x4|4x)

30. limx2(8+6xx2x2)

For the following exercise, use the given information to evaluate the limits: limxcf(x)=3, limxcg(x)=5

31. limxc[2f(x)+g(x)]

32. limxc[3f(x)+g(x)]

33. limxcf(x)g(x)

For the following exercises, evaluate the following limits.

34. limx2cos(πx)

35. limx2sin(πx)

36. limx2sin(πx)

37. f(x)={2x2+2x+1,x0x3,x>0;limx0+f(x)

38. f(x)={2x2+2x+1,x0x3,x>0;limx0f(x)

39. f(x)={2x2+2x+1,x0x3,x>0;limx0f(x)

40. limx4x+53x4

41. limx3+x2x29

For the following exercises, find the average rate of change f(x+h)f(x)h.

42. f(x)=x+1

43. f(x)=2x21

44. f(x)=x2+3x+4

45. f(x)=x2+4x100

46. f(x)=3x2+1

47. f(x)=cos(x)

48. f(x)=2x34x

49. f(x)=1x

50. f(x)=1x2

51. f(x)=x

52. Find an equation that could be represented by Figure 2.

Graph of increasing function with a removable discontinuity at (2, 3).

Figure 2

53. Find an equation that could be represented by Figure 3.

Graph of increasing function with a removable discontinuity at (-3, -1).

Figure 4

For the following exercises, refer to Figure 4.

Graph of increasing function from zero to positive infinity.

Figure 5

54. What is the right-hand limit of the function as x approaches 0?

55. What is the left-hand limit of the function as x approaches 0?

56. The position function s(t)=16t2+144t gives the position of a projectile as a function of time. Find the average velocity (average rate of change) on the interval [1,2] .

57. The height of a projectile is given by s(t)=64t2+192t Find the average rate of change of the height from t=1 second to t=1.5 seconds.

58. The amount of money in an account after t years compounded continuously at 4.25% interest is given by the formula A=A0e0.0425t, where A0 is the initial amount invested. Find the average rate of change of the balance of the account from t=1 year to t=2 years if the initial amount invested is $1,000.00.