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Math Help - Having Trouble Solving An Algebra Equation

  1. #1
    Newbie RyanCouture's Avatar
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    Having Trouble Solving An Algebra Equation

    question is:

    SOLVE:

    4x = 5 = 3(2x+7)

    i havent seen one like this yet, what with all the equal signs

    can anyone gimme some help as to how to go about this?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by RyanCouture View Post
    question is:

    SOLVE:

    4x = 5 = 3(2x+7)

    i havent seen one like this yet, what with all the equal signs

    can anyone gimme some help as to how to go about this?
    where did this equation come from? it makes no sense. there is no real x such that 4x = 5 and 3(2x + 7) = 5

    i'm thinking it should be two equations.

    4x = 5
    => x = 5/4

    and

    3(2x + 7) = 5
    => x = -8/3
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  3. #3
    Newbie RyanCouture's Avatar
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    yeah it doesnt make any sense

    theres no way to re arrange it or anything?
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by RyanCouture View Post
    yeah it doesnt make any sense

    theres no way to re arrange it or anything?
    like i said, the only thing that seems to make sense to me is to have two separate equations. where did this equation come from anyway? was it one that you made up, or was it given to you. tell me the question that you started with
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  5. #5
    Newbie RyanCouture's Avatar
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    it was given to me in a math book:

    2. Solve the following equations:

    a) 4x=5=3(2x+7)

    b) 7x^3+23x+6=0

    c) -64z^2 = -121

    thats the whole segment
    Last edited by RyanCouture; June 3rd 2007 at 02:34 PM.
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  6. #6
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by RyanCouture View Post
    it was given to me in a math book:

    2. Solve the following equations:

    a) 4x=5=3(2x+7)

    b) 7x^3+23x+6=0

    c) =64z^2 = -121

    thats the whole segment
    i think you made a typo. what hinted that to me is the last equation you typed. you had =64z^2 = -121. it makes no sense to have the = in front of the 64 like that. are you sure it shouldn't be a minus sign, as in a - ?

    look at the book again, maybe you should have: 4x - 5 = 3(2x + 7) and -64z^2 = -121
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  7. #7
    Newbie RyanCouture's Avatar
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    lol

    yes your right about question c) there it should be -64z

    but the first one we were talking about is typed correctly, this math course that im doing (its a mail in one) has had MANY typos so far, so i would be surprised if this is one.
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  8. #8
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by RyanCouture View Post
    lol

    yes your right about question c) there it should be -64z

    but the first one we were talking about is typed correctly, this math course that im doing (its a mail in one) has had MANY typos so far, so i would be surprised if this is one.
    yea, its probably a typo. treat the first = sign as a minus. can you do that new equation?
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  9. #9
    Newbie RyanCouture's Avatar
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    i think so

    do i just expand, then collect like terms

    4x-5=3(2x+7)

    4x-5=6x+21

    4x-6x = 5+21

    -2x = 26

    x = 26/-2

    x = -13

    ??

    what do you think?
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  10. #10
    Newbie RyanCouture's Avatar
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    Jhevon ?

    your feedback?

    also if your still there

    how do i go about c)

    -64z = -121

    thanks
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  11. #11
    Senior Member tukeywilliams's Avatar
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    you are right for #1.

    For  -64z = -121 divide both sides by  -64 .

    So:  -\frac{64z}{-64} = -\frac{121}{-64}

     z = -\frac{121}{-64} \approx 1.89

    Remember that a negative number divided by a negative number is a positive number. A negative number multiplied by a negative number is a positive number.
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  12. #12
    Newbie RyanCouture's Avatar
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    whoops, i made a mistake

    the question for c) was:

    -64z = -121

    forgot the square

    do i go about it the same way??
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  13. #13
    Senior Member tukeywilliams's Avatar
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    If the equation is  -64z^{2} = -121 , then:

     -\frac{64z^{2}}{-64} = -\frac{121}{-64}


     z^{2} \approx 1.89


     z \approx \pm \sqrt{1.89} \approx \pm 1.37
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  14. #14
    Newbie RyanCouture's Avatar
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    Quote Originally Posted by tukeywilliams View Post
    If the equation is  -64z^{2} = -121 , then:

     -\frac{64z^{2}}{-64} = -\frac{121}{-64}


     z^{2} \approx 1.89


     z \approx \pm \sqrt{1.89} \approx \pm 1.37
    what does that + square root mean?

    the answer is whatever the square root of 1.89 is?
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  15. #15
    Newbie RyanCouture's Avatar
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    ohh i see, nevermind

    so the answer is 1.37?
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