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Math Help - what does resticted value mean?

  1. #1
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    Exclamation what does resticted value mean?

    Please help me with this question

    State the restricted values of x for 6x-5
    2x(x+4)

    I really am lost on this....

    thanks
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  2. #2
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    Quote Originally Posted by lostone View Post
    Please help me with this question

    State the restricted values of x for 6x-5
    2x(x+4)

    I really am lost on this....

    thanks
    It is when the denominator is zero:

    2x(x+4)=0

    Make each factors zero and solve:
    2x=0 \mbox{ and }x+4=0
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  3. #3
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    ??????

    So that means the answer is zero?

    Quote Originally Posted by ThePerfectHacker View Post
    It is when the denominator is zero:

    2x(x+4)=0

    Make each factors zero and solve:
    2x=0 \mbox{ and }x+4=0
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  4. #4
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    Quote Originally Posted by lostone View Post
    So that means the answer is zero?
    No!

    We need to do both factors.

    1) 2x=0 \Rightarrow x=0
    2) x+4=0 \Rightarrow x=-4.

    Thus,
    x=0,-4 are the two restricted values.
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  5. #5
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    Why would the question be writen with only term "x" if it is used to make 2 different numbers = 0? Like y would it not b writen 6x-5
    2x(y+4)

    X= 0
    y= -4 instead of "x" = 2 different numbers.
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  6. #6
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    Quote Originally Posted by lostone View Post
    Why would the question be writen with only term "x" if it is used to make 2 different numbers = 0? Like y would it not b writen 6x-5
    2x(y+4)

    X= 0
    y= -4 instead of "x" = 2 different numbers.
    There are two possible values for x.

    For example,
    Solve: x^2-1=0.

    If you factor,
    (x+1)(x-1)=0
    Making factors equal to zero we find that,
    x=-1 or x=1.

    Those are the two possible values for x which solve this.

    Same here, it does not mean that there has to be only one value for x there can be two (or more).
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  7. #7
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    so there is no rule that x has to equal 1 number....why would they write it that way? Just to make it more difficult?

    Quote Originally Posted by ThePerfectHacker View Post
    No!

    We need to do both factors.

    1) 2x=0 \Rightarrow x=0
    2) x+4=0 \Rightarrow x=-4.

    Thus,
    x=0,-4 are the two restricted values.
    Quote Originally Posted by ThePerfectHacker View Post
    There are two possible values for x.

    For example,
    Solve: x^2-1=0.

    If you factor,
    (x+1)(x-1)=0
    Making factors equal to zero we find that,
    x=-1 or x=1.

    Those are the two possible values for x which solve this.

    Same here, it does not mean that there has to be only one value for x there can be two (or more).
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  8. #8
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    Quote Originally Posted by lostone View Post
    so there is no rule that x has to equal 1 number....why would they write it that way?
    No there is not rule. Just write
    x = 0 or x=-4.
    That is it.
    Just to make it more difficult?
    Stop complaining.
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  9. #9
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    I really appreciate the help!!! and I'm not complaining just having a hard time that's all.....Thank-you again!!!

    Quote Originally Posted by ThePerfectHacker View Post
    No there is not rule. Just write
    x = 0 or x=-4.
    That is it.

    Stop complaining.
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