Fahrenheit increases at approximately twice the rate of Celsius. (ΔF=1.8ΔC), And freezing for Fahrenheit is 32° (32°F=0°C). Using these facts, we can find the conversion equation F=1.8C+32. Since this is a linear polynomial, there is exactly 1 intersection with the function F=C, which we can find by solving it as a system of equations:
IF C=F AND F=1.8C+32 THEN C=1.8C+32.
C=1.8C+32
C-1.8C=32
-.8C=32
(-8/10)C=32
C=32*(-10/8)
=-32*10/8 [If you’re using a calculator, this is probably your input.]
Why?
Fahrenheit increases at approximately twice the rate of Celsius. (ΔF=1.8ΔC), And freezing for Fahrenheit is 32° (32°F=0°C). Using these facts, we can find the conversion equation F=1.8C+32. Since this is a linear polynomial, there is exactly 1 intersection with the function F=C, which we can find by solving it as a system of equations:
IF C=F AND F=1.8C+32 THEN C=1.8C+32.
C=1.8C+32
C-1.8C=32
-.8C=32
(-8/10)C=32
C=32*(-10/8)
=-32*10/8 [If you’re using a calculator, this is probably your input.]
=-10*32/8
=-10* (32/8)
=-10* (2(5)/2(3))
=-10* (2^(5-3))
=-10* 2^2
=-10* 2*2
=-10* 4
=-40
∴ -40°C = -40°F.