Dear Math Central,
I was very happy to find your website - had a great time browsing around. I am a student at Mount Hood Community College in Gresham, Oregon. I am taking intermediate algebra this summer (Math 95), and have a question for you. My instructor will award extra credit points to any of us who find out how old the formula
y = mx+b is. Would you happen to know the answer?
Thank you for your time,



Hi Beckie,

I am not sure that I can answer your question but I can give you a reference that gives the earliest use of the letter m for the slope of a line. It is in Earliest Uses of Various Mathematical Symbols. Follow the link to "Symbols used in geometry" and scroll down to the note on slope.

I hope this helps,