Slope of a Line for Algebra Dummies

If there's anything we here at the Antisocial Network have learned from plowing through the dross of the internet in search of dumbassery – and we're here to tell you that "needles" and "haystacks" definitely don't apply – it's that far too many people with liberal arts educations are basically clueless when it comes to STEM. Take self-described Mensa member Ryan Menezes, proud owner of a BA in Journalism, who completely blew "How to Find the Slope of a Line Given 2 Points" for eHow. Leaf Group has since moved it to Sciencing.com, where some putz classified it as "physics." Huh.

Menezes almost immediately exposed his tenuous grasp of algebra by defining slope, typical of eHowians forced to write a 75-word introduction:

"A line's slope, or gradient, describes the extent of its slant."

We still haven't figured out what Ryan might have meant by "the extent of its slant"... He then went on to mention horizontal and vertical lines (slope = 0 and slope = ∞, respectively), but nowhere – and we do mean nowhere – did he mention the classical definition of slope, which is rise / run. The closest he got was,

"The slope on the graph is a visual representation of the variable y's rate of change with respect to x..."

...which we find sadly lacking, since slope is not merely a "visual representation" but an intrinsic property. Menezes went on to explain, however, how to calculate the changes in X and Y and use those quantities to calculate the slope: Subtract the second point's y-coordinate from the first's... Subtract the second point's x-coordinate from the first's... Divide the difference between the y-coordinates by the difference between the x-coordinates... this is the slope.

Which, not surprisingly because it's so simple, is correct. What isn't correct is the example Menezes provided for the points (2, 8) and (4, 3):

1. Subtract the second point's y-coordinate from the first's: 8 - 3 = 5.
2. Subtract the second point's x-coordinate from the first's: 2 - 4 = -2.
3. Divide the difference between the y-coordinates by the difference between the x-coordinates: -2 ÷ 5 = -0.4. This is the line's slope

Ummm, no, Ryan, that's not the line's slope: the line's slope is (y2-y1) / (x2-x1), which equals (8 - 3) / (2 - 4), which equals 5 / -2, or -2.5. Menezes got rise and run backwards, which makes his example a classic example of Dumbass of the Day quality.

Oddly, Demand Media replaced a perfectly good tutorial written by Sassyasever with something they didn't bother to proofread, perhaps because it was too "hard." Go figure...

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