Which list of ordered pairs represents solutions to x + y= 2 ?
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Answer:
The solution is similar to the 2-point form of the equation for a line:
y = (y2 -y1)/(x2 -x1)·x + (y1) -(x1)(y2 -y1)/(x2 -x1)
Step-by-step explanation:
Using the two points, write two equations in the unknowns of the equation of the line.
For example, you can use the equation ...
y = mx + b
Then for the points (x1, y1) and (x2, y2) you have two equations in m and b:
b + (x1)m = (y1)
b + (x2)m = (y2)
The corresponding augmented matrix for this system is ...
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The "b" variable can be eliminated by subtracting the first equation from the second. This puts a 0 in row 2 column 1 of the matrix, per <em>Gaussian Elimination</em>.
0 + (x2 -x1)m = (y2 -y1)
Dividing by the value in row 2 column 2 gives you the value of m:
m = (y2 -y1)/(x2 -x1)
This value can be substituted into either equation to find the value of b.
b = (y1) -(x1)(y2 -y1)/(x2 -x1) . . . . . substituting for m in the first equation