Question 857874
are these points collinear? (0,-1) (3,5) and -1,-3)
Put them in order.
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(-1,-3)
(0,-1)
(3,5)
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Add points
(-1,-3)
(0,-1)
(1,y)
(2,y)
(3,5)
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Try the change in y = +2
(-1,-3)
(0,-1)
(1,1)
(2,3)
(3,5)
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They are colinear.
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Or, you can pick 2 of the 3, find the equation of the line thru them, then see if the 3rd point is on the line.