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Question 1087091:  Water freezes at a temperature of 0° on the Celsius scale and 32° on the Fahrenheit scale. Water boils at a temperature of 100° on the Celsius scale and 212° on the Fahrenheit scale.
 
Use this information to express the Celsius temperature C as a linear function of the Fahrenheit temperature F. Enter exact answers only, no approximations.
 
C(F)=
 
Determine when the temperature reading on the Celsius scale is twice the temperature reading on the Fahrenheit scale. Enter exact answers only, no approximations. 
 
 Answer by Alan3354(69443)      (Show Source): 
You can  put this solution on YOUR website! Water freezes at a temperature of 0° on the Celsius scale and 32° on the Fahrenheit scale. Water boils at a temperature of 100° on the Celsius scale and 212° on the Fahrenheit scale.
 
Use this information to express the Celsius temperature C as a linear function of the Fahrenheit temperature F. 
100 degs change in C = 180 degs change in F 
--> F = 1.8*C + k where k is a constant. 
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F = 1.8*C + k 
32 = 1.8*0 + k 
k = 32 
--> F = 1.8C + 32 
C = (F - 32)/1.8 or (F-32)*5/9
 
C(F)= 5(F-32)/9 
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Determine when the temperature reading on the Celsius scale is twice the temperature reading on the Fahrenheit scale. Enter exact answers only, no approximations. 
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C(F)= 5(F-32)/9 
2F = 5(F-32)/9 
18F = 5F - 160 
13F = -160 
F = -160/13 
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C = 5*(-160/13 - 32)/9 = (-800/13 - 2080/13)/9 
C = -320/13 degs 
 
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