53、32; eight

54、60

55, -2 or 0

56、5

57, isosceles right triangle

58. Two-thirds root number three

59.x is greater than or equal to 1 and less than 3.

60、4

6 1、6,8, 10

62,47 degrees

63, 1440 degrees; 36 degrees

64、84

65、=

66. Root number five

67. Three sevenths

68, to the sixteenth power l.

69、4(a+b)

70, three sevenths

7 1, four fifths

72、S=4n-4

73、 10

74、7.5

75、 1

76. Minimum value: 130

Maximum value: 738

78、ab

79, the circumference is equal

80、30

score points