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| Question 132226:  find the value of r so the line that passes through each pair of the points has the given slope.
 1) (1,4) (r,5), m= undefined
 Answer by nycsharkman(136)
      (Show Source): 
You can put this solution on YOUR website! Note that when the line of the graph is vertical the slope is undefined. You were given two points:
 (1,4) and (r,5)
 The slope is undefined.  This means that the value of r must be a value that produces division by zero, which is not allowed in math.
 What could be the value of r?
 undefined slope = (5 - 4)/(r -1)
 The only answer that makes sense is r = 1.  When r is 1, we get a ZERO in the denominator of this fraction, which makes the slope undefined.
 How did I get 1 for r?  I set the denominator (r - 1) to zero and solved for r.
 r - 1 = 0
 r = 1
 Got it?  Is this clear?
 
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