Answer:
y = (-2/3)x - 1/3
Explanation:
Find the equation of the line through the two points (-2, 1) and (1, -1).
As we increase x from -2 to 1 (an increase of 3), y decreases from 1 to -1 (a decrease of 2).
Thus, the slope of this line is m = rise / run = -2/3.
Using the slope-intercept formula y = mx + b, and substituting the givens m = -2/3, x = -2 and y = 1, we get:
1 = (-2/3)(-2) + b, or
1 = 4/3 + b, or 3/3 = 4/3 + b.
Then b must be 3/3 - 4/3, or -1/3, and the equation of the line is then
y = (-2/3)x - 1/3