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How do the slopes of lines relate to the number of solutions in a system of linear equations?
Example Solution: y=2x+1 & (I) y=2x+4 & (II)
Graph:
Let's analyze the relation between the number of solutions in a system of linear equations and the lines representing these equations.
One Solution | No Solution | Infinitely Many Solutions |
---|---|---|
Lines intersect | Lines are parallel | Lines are the same |
Lines have different slopes | Lines have the same slopes but different y-intercepts | Lines have the same slopes and y-intercepts |
In our exercise, we want to write a system of linear equations that has no solution. To do this, we can write two lines that have the same slope but different y-intercepts. y= 2x+ 1 & (I) y= 2x+ 4 & (II) Now we will use a graph to make sure that our example system is correct. Let's plot points (0, 1) and (0, 3) that represent the y-intercepts of both equations.
Next we will use the slope to draw another point for each line. Since both lines have a slope of 2, we will start at the y-intercepts and then move 1 unit right and 2 units up.
Finally we will connect the points with smooth lines.
We can see that the lines are parallel, so they do not have any point of intersection. This confirms that there is no solution to our example system.