Answer:
y = - x - 1
Step-by-step explanation:
the equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
calculate m using the slope formula
m = 
with (x₁, y₁ ) = (- 1, 0) and (x₂, y₂ ) = (0, - 1) ← 2 points on the line
m =
=
=
= - 1
the line crosses the y- axis at (0, - 1 ) ⇒ c = - 1
y = - x - 1 ← equation of blue line