Question 471105
<pre>
The line whose equation is x = 7 is this green vertical line:

{{{drawing(325,325,-10,10,-10,10,

graph(325,325,-10,10,-10,10), green(line(7,11,7,-11)) )}}}

It has no slope and no y-intercept, thus it cannot be written

in the slope-intercept form y=mx+b

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The line whose equation is y = 4 is this green horizontal line:

{{{drawing(325,325,-10,10,-10,10,

graph(325,325,-10,10,-10,10), green(line(11,4,-11,4)) )}}}

It has slope = 0 and y-intercept (0,4). It can be written

in the slope-intercept form 

y = mx + b 

as

y = 0x + 4

Edwin</pre>