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| Question 1178983:  Solve the following inequality
 
  >   Answer by ikleyn(52866)
      (Show Source): 
You can put this solution on YOUR website! . Solve the following inequality
  > x-1 ~~~~~~~~~~~~~~~
 
 
 This inequality is  SPECIAL  and its solution requires  ACCURACY - so trace attentively each my step.
 
 
 
 
1.  The domain of this inequality is the set  7-x >= 0,  or   x <= 7.
2.  All the set  x-1 < 0,  or  x < 1,  is the solution, BECAUSE the right side is negative there, 
                                                         while the left side is not negative.
    Therefore, we need analyze for the solution only the remaining part  1 <= x <= 7.
    Let's call this set { 1 <= x <= 7 } as A17.
3.  Next, analyzing for the set A17, square both sides of the original inequality.  You will get
        7 - x > x^2 - 2x + 1
        x^2 - x - 6 < 0
        (x-3)*(x+2) < 0
    The solution set to the last inequality  is   -2 < x < 3.      
    Taking the intersection with the set A17, we have the solution set  { 1 <= x <3 }.
4.  Thus we have two parts of the entire solution set  (a)  { x < 1 }  from n.2,  and  (b) { 1 <= x < 3 } from n.3.
     The final solution set is the union  sets (a) and (b), i.e.  { x < 1 } U { 1 <= x < 3},  which is,  OBVIOUSLY,  (-oo < x < 3 }.
ANSWER.  The solution to the original inequality is the set  { -oo < x < 3 },  or  (-oo,3).
                          Visual CHECK
     Plot  y =  (red line)  and  y = x-1  (green line)
The solution set is the set of all points of the x-axis, where red line is above the green line.
 Solved,  answered,  explained,  visualized,  checked and completed.
 
 
 
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 The post-solution noteThe plot is indispensable helper in such an analysis.
 
 Honestly,  it is THE  PLOT,  who directs and guides the flow of your mental reasonings.
 
 
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 Do not forget to post your  "THANKS"  to me for my teaching.
 
 
 
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