SOLUTION: Solve the following rational inequalties for the given variable x+3/2x<2

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Question 751237: Solve the following rational inequalties for the given variable
x+3/2x<2

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
%28x%2B3%29%2F2x < 2

Subtract 2 from both sides to get 0 on the right:

%28x%2B3%29%2F2x - 2 < 0

Get a common denominator of 2x.  Multiply the 2 by 2x%2F%282x%29

%28x%2B3%29%2F%282x%29 - 2·2x%2F%282x%29 < 0

%28x%2B3%29%2F%282x%29 - 4x%2F%282x%29 < 0

%28%28x%2B3%29-4x%29%2F%282x%29 < 0

%28x%2B3-4x%29%2F%282x%29 < 0

%283-3x%29%2F%282x%29 < 0

Factor the numerator

%283%281-x%29%29%2F%282x%29 < 0

Divide both sides by 3

%281-x%29%2F%282x%29 < 0

Multiply both sides by 2

%281-x%29%2Fx < 0

Find all critical values by setting numerator and denominator = 0

 1-x=0        x=0
  -x=-1       
   x=1  

So the critical values are 0 and 1

Put these on a number line:

----------o--o---------
-3 -2 -1  0  1  2  3  4

test a value to the left of 0, say x=-1

Substitute it in

%281-x%29%2Fx < 0

%281-%28-1%29%29%2F%28-1%29 < 0

%281%2B1%29%2F%28-1%29 < 0

2%2F%28-1%29 < 0

-2 < 0

This is true so we shade the portion of the
number line left of 0

< ==========o--o---------
  -3 -2 -1  0  1  2  3  4

test a value between 0 and 1 say x=0.5

Substitute it in

%281-0.5%29%2F0.5 < 0

0.5%2F0.5 < 0

1 < 0

That is false so we do not shade the portion of the
number line between 0 and 1.  So we still have

< ==========o--o---------
  -3 -2 -1  0  1  2  3  4

We test a value to the right of 1, say x=2

Substitute it in

%281-x%29%2Fx < 0

%281-%282%29%29%2F2 < 0

%28-1%29%2F2 < 0

-1%2F2 < 0


This is true so we shade the portion of the
number line right of 1

<  =========o--o======== >
  -3 -2 -1  0  1  2  3  4

That's the graph of the solution set, in interval notation
that is

%28matrix%281%2C3%2C%0D%0A%0D%0A-infinity%2C%22%2C%22%2C0%29%29U%28matrix%281%2C3%2C%0D%0A%0D%0A1%2C%22%2C%22%2Cinfinity%29%29

Edwin