Question 341309:  Find the linear equation that passes through the point (-8,1)  and has an undefined slope. 
 
Write the equation of the line parallel to x=8 that passes through the point   (-3,0). 
 
Find the slope of the line passing through the points (-4,2) and (1,-5). 
 Answer by texttutoring(324)      (Show Source): 
You can  put this solution on YOUR website! Undefined slope means that the slope is dividing by zero. So there is no 'run'. It is a straight up and down, vertical line. If it passes through (-8,1) then the line must be x = -8. 
 
 
A line parallel to  x = 8 would also have an undefined slope, meaning it is a vertical line. If it passes through the point (-3,0) then it must be x=-3. It's a vertical line at x=-3.
 
 
Lastly, if a line passes through (-4,2) and (1,-5). First find the slope:
 
 
m = (y2-y1) / (x2-x1) 
m = (-5 - 2) / (1 - -4) 
m = -7 / (1+4) 
m = -7 / 5
 
 
Now put this value for m into y=mx+b, and use either point, (-4,2) or (1,-5) to solve for b:
 
 
y=mx+b 
-5 =(-7/5)(1) + b 
-5 + 7/5 = b 
b = -18/5
 
 
The equation of the line is thus y = (-7/5)x -18/5
 
 
Hope this helps! Let me know if you're confused by anything I wrote. 
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