Question 984926
The vertical line passes through (4,1) means
We want the vertical line that passes through all points with x coordinate equal to 4.
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note that the slope of a vertical line is undefined since (x2 - x1) is 0 for all points on the vertical line, for this problem (4 - 4).
note that slope is defined as (y2 - y1) / (x2 - x1)
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x = a is the equation where a is the point where the line crosses the x axis, therefore
x = 4 is the answer