SOLUTION: This is giving me troubles please help me. Solve {{{abs((2x-1)/5)}}} <u>></u> {{{5/6}}}

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Question 87518: This is giving me troubles please help me. Solve abs%28%282x-1%29%2F5%29 > 5%2F6
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
This is giving me troubles please help me. Solve abs%28%282x-1%29%2F5%29 > 5%2F6
Rules for getting rid of absolute value symbols in inequalities,
The word "EXPRESSION" refers to whatever expression is between the
absolute value symbols: 

1.  |EXPRESSION| < A is equivalent to: -A < EXPRESSION < A

2.  |EXPRESSION| < A ie equivalent to: -A < EXPRESSION < A

3.  |EXPRESSION| > A ie equivalent to: EXPRESSION < -A OR EXPRESSION > A

04.  |EXPRESSION| > A ie equivalent to: EXPRESSION < -A OR EXPRESSION > A

abs%28%282x-1%29%2F5%29 > 5%2F6

This is case 4 with EXPRESSION = 2x-1%29%2F5 and A = 5%2F6

Thus it is equivalent to:

2x-1%29%2F5 < -5%2F6 OR 2x-1%29%2F5 > 5%2F6

Multiply both sides of both inequalities by 30 to clear of fractions:

+%28+30%282x-1%29+%29%2F5+ < %28%2830%29%28-5%29%29%2F6+ OR %2830%282x-1%29%29%2F5+ > %28%2830%29%285%29%29%2F6

6(2x - 1) < -25  OR  6(2x - 1) > 25

  12x - 6 < -25  OR  12x - 6 > 25

      12x < -19  OR  12x > 31

       x < -19%2F12  OR  x > 31%2F12     

Make three number lines:

Draw three number lines with a closed circle 
at the boundary points (closed because it's 
"<" OR ">" and not "<" OR ">"):

x <-19%2F12                  
-----------l-------------l----------
        -19%2F12            31%2F12      

x >31%2F12                     
-----------l-------------l----------
        -19%2F12            31%2F12 
                                                                            
x <-19%2F12 OR x > 31%2F12  
-----------l-------------l----------
        -19%2F12            31%2F12

Shade the first one to the left of -19%2F12, because
"less than" is "left":

x <-19%2F12
<==========l-------------l----------
        -19%2F12            31%2F12   

Shade the second one to the right of 31%2F12, because
"greater than" is "right":

x > 31%2F12
-----------l-------------l==========>
        -19%2F12            31%2F12  

Now since the word between the inequalities is "OR" 
and not "AND", we shade all parts of the final
number line if it is shaded on the first one OR if 
it is shaded on the second one.

So the final number line is:

x <-19%2F12 or x >31%2F12  
<==========l-------------l==========>
        -19%2F12            31%2F12    

Now we imagine that there is a "negative infinity"
on the far left and an "infinity" on the far right.

So the interval notation is

(-oo, -19%2F12] U [31%2F12, oo)


Edwin