Question 883103
That equation is in point-slope form.  This form shows you the slope and a point on the line.


Assuming you know and understand the formula for slope of a line, you could have a variable point (x, y) and a known given point (u, v).  Slope is vertical change divided by horizontal change:


{{{m=(y-v)/(x-u)}}}.
You have seen, studied, and exercised with this formula.


Try multiplying the left side and the right side of the formula by {{{x-u}}}.
{{{m*(x-u)=y-v}}}
{{{highlight_green(y-v=m(x-u))}}}, point-slope form.
You can see plainly the placement of the the slope, m; and the coordinates of the included known point (u, v).


Compare the two forms:
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y-v=m(x-u)
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y-4=-(x-1)
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