Question

Which is an equation of the line with slope -3 and passes through (2,-1)?

Answer 1

Using the equation
(y-y1) = m(x-x1)
Where x1 and y1 are points that lie on the line and m is the slope.
These, be plugging in the values given, we get
(y-(-1))=(-3)(x-2)
(y+1)=(-3x+6)
y+3x-5=0 is the required equation.