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Topic: Fw: [math-learn] Confusion between slope and coordinates
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Ron Ferguson

Posts: 949
Registered: 12/3/04
Fw: [math-learn] Confusion between slope and coordinates
Posted: Feb 15, 2001 11:40 AM
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I usually try to call the slope interchangeably delta y / delta x OR change
in y over change in x. The it doesn't matter which they do first: -2/3 is
change y by -2 and change x by 3. So long as they know which is which they
can still choose to change x first and read that change as 3 with an
associated change in y of -2. Finally re-express -2/3 as an equivalent
ratio such as 4/(-6) and you can still correctly locate another point by
"simultaneously" changing y by 4 and x by -6.

Moreover I emphasize that the slope is a rate (ratio) as usually indicated
by the key word "per" which indicates a quotient (cf. miles per hour, price
per pound, per cent, etc.) From these I indicate the "clues/check" that
positive rates indicate increasing and negative rates indicate decreasing.


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