Question

Write the standard form of the equation of line through (3, -1) with a slope of -1.

Answer 1

The standard form of a line: $Ax+By=C$.

The point-slope form: $y-y_1=m(x-x_1)$

We have the point (3, -1) and the slope m = -1. Substitute:

$y-(-1)=-1(x-3)$

$y+1=-x+3$                    add x to both sides

$x+y+1=3$             subtract 1 from both sides

$\boxed{x+y=2}$