85. Yes, because there is only one high temperature every day

87. No, because Nevada and North Carolina both start with N

89. $A(x)=x^2;A(4)=16;A(4)$ represents the area of a square tile with side of length 4.

91. It is a function. $S(x)=6x^2;S(3)=54$

93.

1. [0, 8]

2. $h(2)=192,h(4)=256,h(6)=192$

3. 8 sec

4. 

95. $P=28x-x^2$

97. $S=2x^2+{\displaystyle \frac{256}{x}}$

99. $A={\displaystyle \frac{x^2}{4\pi }}+{\displaystyle \frac{1}{16}}{(20-x)}^2$

101. $C=2x^2+{\displaystyle \frac{6912}{x}}$

103. $d={[{(x-2)}^2+{(x^3-3x+5)}^2]}^{1/2}$

105.

1. $p(5)=1150;$ if 5000 TVs can be sold, the price per TV is $1150. $p(15)=900;$ if 15,000 TVs can be sold, the price per TV is $900. $p(30)=525;$ if 30,000 TVs can be sold, the price per TV is $525

2. 

3. $p(25)=650;$ if the TVs are priced at $650 each, 25,000 can be sold.

107.

1. $C(x)=5.5x+75\text{,}000$

2. $R(x)=9x$

3. $P(x)=3.5x-75\text{,}000$

4. 21,429

5. $86,000