Monday, August 15, 2011

Solve the nonlinear inequality that has the variable in the denominator. 2/x+3=

We have to solve
2/x+3=<1/x-3


2/(x+3)=<1/(x-3)


=>
2/(x+3) - 1/(x-3) =< 0


=> [2(x-3) - (x+3)]/(x
- 3)(x + 3) =< 0


=> (2x - 6 - x-3)/(x - 3)(x
+ 3) =< 0


=> (x-9)/(x - 3)(x + 3) =<
0


This is less than or equal to 0 if one of the terms is
less than 0 or all the three terms are less than or equal to
0.


If all the three terms are less than or equal to
0:


  • (x-9)=< 0 , (x - 3) =< 0 and (x
    + 3) =< 0

=> x=< 9 ,
x=< 3, x=< -3


x=< -3 satisfies all the
three conditions.


If one of the terms is less than or equal
to 0:


  • x=< 9 , x > 3 and x >
    -3

=> 9 >= x >
3


  • x=< 3 , x > 9 and x > -3
    , gives no solutions

  • x=< -3 ,
    x > 3 and x > 9, gives no
    solutions.

Therefore the values
of x are (-inf , -3] U (3 ; 9]

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