Question 510120
If x=4 there is no slope and there is no y-intercept.
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x=4 defines a vertical line that goes through x=4.
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y can take on any value from -infinity to +infinity, but there is no defined slope
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Recall the slope = change in y / change in x
There is no change in x, so we are attempting to divide by 0.
Dividing by zero is undefined.
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In slope-intercept form:  y = mx+b,
the y-intercept is 'b', defining the point (0,b).
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But we're told x=4, so there is no point where x=0.
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Done.