Question 1139366
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There are many formal mathematical methods for finding the answer.  One of them is what the other tutor did; find the equation determined by two of the points and see if the third point satisfies that equation.<br>
That's mathematically valid; but not very efficient.<br>
I would find the answer by comparing the slopes between pairs of points.<br>
And I would find the answer by using my UNDERSTANDING of slopes, rather than using the formal mathematical definition of slope.<br>
Picture the three given points; from left to right, the points are C, A, B.  Determine how far you move to the right, and how far you move up or down, to get from C to A.  Then do the same from A to B.<br>
C(-2,4) to A(1,3): right 3, down 1.<br>
A(1,3) to B(4,2): right 3, down 1.<br>
If you have a basic understanding of slope, those results tell you that the slope from C to A is the same as the slope from A to B; therefore the three points lie on the same line.