Rainboe, Interesting linear formula for the normally expected temperature range, it seems reasonably accurate for day to day purposes
The exact formula,
dirka, which is not linera, is -
TAS = 38.975 X SQR SAT X Mach Number,
Where, TAS is in Knots, and SAT (Static Air Temperature) is Degrees Absolute in Kelvin, i.e. °C + 273.15
The constant of 38.975 does suffer from a bit of Rounding Up/Down, depending upon the source of information, NASA's formulae work for me
If you look at both of the posts following your question,
dirka, Hotter = Faster; Colder = Slower.
Regards,
Old Smokey