# Thread: Celcius Conversion

1. ## Celcius Conversion

I know there is a simple way to solve this question, but I can't figure out how to set up the next step of the problem.

If Fareinheit temperature is 85, and the formula for Celsius conversion is 9/5C+32, what is the Celsius temperature?

2. ## Re: Celcius Conversion

The Celsius to Fahrenheit conversion is F = (9/5) C + 32. To go the other way, you must invert this linear function. How do you do that?

3. ## Re: Celcius Conversion

Originally Posted by Ackbeet
The Celsius to Fahrenheit conversion is F = (9/5) C + 32. To go the other way, you must invert this linear function. How do you do that?
Correct me if I'm wrong. (I get these questions from strictly timed practice tests. So to meet the time requirement, I don't have time to solve the problem in detail, and review and memorize rules later)

C= F(5/9)-32?

4. ## Re: Celcius Conversion

That's incorrect. To invert, you must switch the roles of F and C, and then solve for C. What do you get?

5. ## Re: Celcius Conversion

No. You must perform subtraction before dividing because of the order of operations

6. ## Re: Celcius Conversion

Originally Posted by Ackbeet
That's incorrect. To invert, you must switch the roles of F and C, and then solve for C. What do you get?
I looked up the formula, and I am finding 2 conflicting equations. I see C= (5/9)F-32, and C=(5/9) * (F-32)

I am more confused now than I was before.

7. ## Re: Celcius Conversion

The second equation is correct, the first is not. See here. From the original formula, as e^(i*pi) said, you must first subtract the 32, and then multiply by 5/9.

F= 1.8 c +32
f -32/1.8 =c

9. ## Re: Celcius Conversion

Ah I see now. Thank you all very much for your help.

10. ## Re: Celcius Conversion

If Fareinheit temperature is 85, and the formula for Celsius conversion is 9/5C+32, what is the Celsius temperature?
Instead of solving for the general "inverse" you could just solve the equation
85= (9/5)C+ 32 for C.

11. ## Re: Celcius Conversion

Originally Posted by KingNathan
I looked up the formula, and I am finding 2 conflicting equations. I see C= (5/9)F-32, and C=(5/9) * (F-32)

I am more confused now than I was before.
When in doubt, CHECK!

-40ºC = -40ºF

0ºC = 32ºF

40ºC = 104ºF

100ºC = 212ºF

Memorize these four.

You may also want 37ºC = 98.6ºF

12. ## Re: Celcius Conversion

Originally Posted by TKHunny
When in doubt, CHECK!

-40ºC = -40ºF

0ºC = 32ºF

40ºC = 104ºF

100ºC = 212ºF

Memorize these four.

You may also want 37ºC = 98.6ºF
Excellent advice. Excellent.