Step-by-step explanation:
for a linear function the rate of change is constant everywhere.
that means that
(f(a) - f(b))/(a - b)
is constant (the same value) for all possible values of a and b.
looking at the graphic I see several "nice" points (points with integer coordinates).
e.g. (0, 1), (1, -1)
as you know, for functions and their point coordinates, the x-values are the arguments in the function (like a and b), and the y-values are the function results.
so, we get
a = 1, b = 0, f(1) = -1, f(0) = 1
(-1 - 1) / (1 - 0) = -2/1 = -2
the common rate of change (also called e.g. slope) of this line is -2.
that means every time we increase x by 1, y changes by -2 (the line goes down from left to right).
