Why is the letter m used for slope in equations?
This question has been researched by math historians but has not yet been answered definitively. Many people have been taught that m comes from the French monter, to climb, but this appears to be an ‘urban legend.’ Although m can stand for “modulus of slope” and the term “modulus” has often been used for “the essential parameter determining,” there is no definitive proof that this is the derivation of m. M. Risi, the author of math textbooks written in French for students of Quebec province, says that in his system, “the first letters of the alphabet, a, b, c… represent the constants, the last letters, x, y, z, represent the unknown variables, and the middle letters, m, n, p… represent the parameters.” When he started to explain slope, it was in studying the first degree equation: y = mx + b. X and y were the variables, b was fixed and considered as a constant, and was appended to the coefficient of x as its value varied–so it was a parameter, and that is why m was selected. Prof.
