Question 276136
{{{drawing(
500, 500, -5, 5, -5, 5,
grid(1),
graph(
500, 500, -5, 5, -5, 5,
x+4,-2x+1))}}}


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*[tex \LARGE \ \ \ \ \ \ \ \ \ \ y\ =\ x\ +\ 4] is the red line


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ y\ =\ -2x\ +\ 1] is the green line


A graph of a straight line is an infinite number of ordered pairs such that the coordinates of each ordered pair satisfies the equation.  When, as in this case,  two lines intersect in a single point, that single point has the characteristic that its coordinates satisfy BOTH equations simultaneously.  Therefore, that single point is the single element in the solution set of the SYSTEM of equations.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
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