Teacher2Teacher Q&A #374

Reason for using "m" and "b" in y=mx+b

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From: Marielouise (for Teacher2Teacher Service)
Date: Jul 12, 1998 at 15:49:30
Subject: Re: Reason for using "m" and "b" in y=mx+b

Michelle, You have asked an age old question: "Why is m used to denote the slope?" Math historians do not know. Traditionally there is an answer given for the use of "b" for the y-intercept. When graphing in three space: (a,0,0) is the point where the x-axis intersects the line or plane; (0,b,0) is the point where the y-axis intersects and (0,0,c) is the point where the z-axis intersects. The value of "b" is then the value on the y-axis or the y- intercept. Similarly "a" and "c" are the x-intercept and the z-intercept. In two dimensional space there are only two axes and two possible intercepts. Have you ever considered the two intercept form of a line? It is (x/a) + (y/b) = 1, where a and b are the x-intercept and y-intercept. -Marielouise, for the Teacher2Teacher service

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