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-   -   Compound inequalith (https://www.askmehelpdesk.com/showthread.php?t=2853)

  • Sep 23, 2004, 09:03 PM
    tazz
    compound inequalith
    ?? The problem is 6x-4>2x or 4x-1 < x+5. Please show me how to solve this > Thanks
  • Sep 27, 2004, 08:00 AM
    melanie.albury
    Re: compound inequalith
    Hi,

    This works just like solving an equation with an equals sign. If you add something to one side you have to add it to the other, and the same for subtract, multiply, divide etc.

    So for the first one you have 6x - 4 > 2x.

    taking away 2x from both sides you get:

    6x - 2x - 4 > 0
    4x - 4 > 0

    adding 4 to both sides you get:

    4x > 4

    dividing both sides by 4 you get:

    x > 1.

    [The other way of looking at problems like this is to move numbers from side to side - by this I mean to go from
    6x - 4 > 2x
    to
    6x - 2x - 4 > 0

    you can say that in the first one, take the 2x over to the other side. Every time you swap sides, you swap signs, so a + goes to a - and a - goes to a +. So at the moment it is +2x, if you take it to the other side it becomes -2x.

    The same works for moving the 4:

    4x - 4 > 0
    move the -4 to the other side, swap the signs so it becomes +4:

    4x > 4

    and the same works again for the multiply - 4x is the same as 4*x (4 multiplied by x). When you take the 4 over to the other side, it becomes a divide.

    so 4*x > 4 becomes

    x > 4/4 = 1]

    So overall the first equation gives you x > 1.

    You should now be able to work out the second one. If you have any problems, let me know!

    x
  • Sep 27, 2004, 09:25 AM
    tazz
    Compound inequalith
    Thanks for your help. :)

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