SOLUTION: find the slope of a line that is perpendicular to the y-axis and passes through the point(-7,8)

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Question 1206470: find the slope of a line that is perpendicular to the y-axis and passes through the point(-7,8)
Found 2 solutions by Theo, ikleyn:
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
a line parallel to the x-axis has the form y = k.
a line parallel to the y-axis has the form x = k.

a line is formed by two points.
the points are (x1,y1) and (x2,y2)

the slope of the line is equal to (y2 - y1) / (x2 - x1)

if the line is parallel to the x-axis, then y2 = y1 and the slope becomes 0 / (x1 - x1) = 0.

if the line is parallel to the y-axis, then x2 = x1 and the slope becomes (y2 - y1) / 0 which is undefined.

if the slope is 0, the line is parallel to the x-axis.
if the slope is undefined, the line is parallel to the y-axis.

if the line is parallel to the x-axis, it is perpendicular to the y-axis.
if the line is parallel to the y-axis, it is perpendicular to the x-axis.

your line is perpendicular to the y-axis which means it is parallel to the x-axis.

that means that y2 = y1 which means that the slope is 0.

the equation of your line is therefore y = 0x + b which becomes y = b, where b is the y-intersect.

the line passing through the point (-7,8) and perpendicular to the y-axis is the line y = 8.

x can be any value and the y-value will always be 8.

here's the graph.



you can see that, no matter what the value of x is, y will always be 8.

you can see that the line is parallel to the x-axis which makes it perpendicular to the y-axis.

the x-axis is a horizontal line at y = 0.
the y-axis is a vertical line as x = 0.



Answer by ikleyn(52864) About Me  (Show Source):
You can put this solution on YOUR website!
.
find the slope of a line that is perpendicular to the y-axis and passes through the point(-7,8)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To answer this question, you should not make any calculations, and the given coordinates
of the point are excessive unnecessary information.

Any straight line in a coordinate plane, perpendicular to y-axis, is parallel to x-axis and has zero slope.


That is all.