How do you plot (-3, 2 ), (-2, 1), (1, -2)?

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Answer 1 · 2015-08-01T20:08:12

These three points are colinear, lying on the line:

#y=-x-1#

You can calculate the slope #m# of a line through any pair of points #(x_1, y_1)# and #(x_2, y_2)# using the formula:

#m = (Delta y)/(Delta x) = (y_2 - y_1) / (x_2 - x_1)#

So the slope of a line through #(-3, 2)# and #(-2, 1)# is:

#(1 - 2)/(-2 - (-3)) = -1/1 = -1#

The slope of a line through #(-2, 1)# and #(1, -2)# is:

#(-2 - 1) / (1 - (-2)) = (-3)/3 = -1#

So these three points are colinear with slope #-1#.

Then since the line passes through #(1, -2)#, we know:

#y+2 = -1(x-1) = -x+1#

Subtract #2# from both sides to get:

#y = -x-1#

graph{(y+x+1)((x+3)^2+(y-2)^2-0.02)((x+2)^2+(y-1)^2-0.02)((x-1)^2+(y+2)^2-0.02) = 0 [-10.96, 9.04, -4.96, 5.04]}