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SOLVING EQUATION

by NEKORIA
(CHARLOTTE, N.C)











































The formula C = 5/9 (F -32) gives the Celsius temperature C in terms of the Fahrenheit temperature F. Transform the formula to find Fahrenheit temperature in terms of Celsius temperature. Then find the Fahrenheit temperature when the Celsius temperature is 20 degrees.

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Jun 28, 2010
Solving Equation
by: Staff


The question:

The formula C = 5/9 (F -32) gives the Celsius temperature C in terms of the Fahrenheit temperature F.

1. Transform the formula to find Fahrenheit temperature in terms of Celsius temperature.
2. Then find the Fahrenheit temperature when the Celsius temperature is 20 degrees.

The answer:


1. Solve for “F”

Write the original equation

C = 5/9 (F -32)

Step A: eliminate the fraction 5/9 from the right side of the equation by multiplying each side of the equation by its reciprocal, 9/5
(why ? : multiplying a non-zero number by its reciprocal always equals 1, which means the 5/9 will completely disappear from the right side of this equation. 9/5 is called the multiplicative inverse of 5/9.)

(9/5) x C = (9/5) x (5/9) x (F – 32)

(9/5) x C = 1 x (F – 32)

(9/5) x C = F – 32

(9/5) C = F – 32



Step B: eliminate the -32 from the right side of the equation by adding +32 to each side of the equation.

(why ? : when any number and its additive inverse are added [in this example: -32 and +32], the result is always zero. The -32 will disappear from the right hand side of the equation.)

(9/5) C = F – 32

(9/5) C + 32= F – 32 + 32

(9/5) C + 32= F + 0

(9/5) C + 32= F

The final answer is: F = (9/5)C + 32



2. find the Fahrenheit temperature when the Celsius temperature is 20 degrees


Write the original equation

F = (9/5)C + 32

Substitute 20 degrees for “C”

F = (9/5)C + 32

F = (9/5) x 20 + 32

F = (9 x 4) + 32

F = 36 + 32

F = 68

The final answer is: F = 68 degrees


Nekoria,

You can check the final calculation by going to the following web site:

http://www.lenntech.com/calculators/temperature/temperature.htm

Just type in the number 20 for Celsius, then press calculate.






Thanks for writing.


Staff
www.solving-math-problems.com


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