$A$'s coordinates are $(6,5)$ and $B$'s are $(2,-1)$. I have tried time and time again to do this but keep ending up with $c$ (from $y=mx + c$) as $-4$ when it should be $8$, can anyone help?
Show that the line $AB$ has the equation $3x - 2y = 8$
3
$\begingroup$
geometry
1 Answers
4
You did it right.
$3x-2y = 8 \Longrightarrow -2y = 8-3x \Longrightarrow y = \frac{3}{2}x-4$
Your only mistake was that you didn't work the above chain "backwards" to show that your $y=mx+b$ form is equivalent to what is sometimes called the "parametric form" of a line: $c_1x+c_2y = k$.
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0ive never been taught that so thats really helpful! – 2012-09-18