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Math Help - A few problems I can't work out!

  1. #1
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    A few problems I can't work out!

    q/t=q/p+1 Express p in terms of q & t
    (I'm using / as a fraction thing)

    Solve 2 over x-1 minus 3 over x+1 equals 1 over 15

    (12-2x)(10-2x)=80
    Find the value of x

    Thanks for any help, I'll probably need more
    Last edited by 1488ID; January 6th 2009 at 07:10 AM.
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  2. #2
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    Re :

    (1) \frac{q}{t}=\frac{q}{p}+1
    \frac{q}{t}-1=\frac{q}{p}
    finally i get p=\frac{qt}{q-t}

    (2) \frac{2}{x-1}-\frac{3}{x+1}=\frac{1}{15}
    Try equating the denominator first
    \frac{2(x+1)-3(x-1)}{(x-1)(x+1)}=\frac{1}{15}
    After that cross multiply and solve for x ..


    (3) (12-2x)(10-2x)=80
    some expansion is required here
    120-24x-20x+4x^2-80=0
    Can u continue from here ?
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  3. #3
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    Thanks very much. Is it a quadratic equation I need to work out for the last one?
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  4. #4
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    Quote Originally Posted by mathaddict View Post
    (1) \frac{q}{t}=\frac{q}{p}+1
    \frac{q}{t}-1=\frac{q}{p}
    finally i get p=\frac{qt}{q-t}
    Em where does the -1 go?
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  5. #5
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    Re :

    Quote Originally Posted by 1488ID View Post
    Thanks very much. Is it a quadratic equation I need to work out for the last one?

    Yes .
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  6. #6
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    Re :

    Quote Originally Posted by 1488ID View Post
    Em where does the -1 go?

    note that \frac{q}{t}-1=\frac{q-t}{t}
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  7. #7
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    Quote Originally Posted by mathaddict View Post
    note that \frac{q}{t}-1=\frac{q-t}{t}
    What mathsaddict has done is made 1 into \frac{t}{t} and then solved from there
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  8. #8
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    2 - 3 =
    x-1 x+1

    cross multiplying

    2(x+1) 3(x-1) = 1
    (x-1)(x+1) 15

    15(5-x) = x2 1
    X2 + 15x- 76=0
    Factorising
    X2+4x+19x-76=0
    Becomes
    X(x+4)-19(x+4) = 0
    Therefore x= -4 and 19
    Attached Files Attached Files
    • File Type: doc 2.doc (23.5 KB, 14 views)
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  9. #9
    Super Member craig's Avatar
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    Quote Originally Posted by correct View Post
    2 - 3 =
    x-1 x+1

    cross multiplying

    2(x+1) 3(x-1) = 1
    (x-1)(x+1) 15

    15(5-x) = x2 1
    X2 + 15x- 76=0
    Factorising
    X2+4x+19x-76=0
    Becomes
    X(x+4)-19(x+4) = 0
    Therefore x= -4 and 19

    Correct
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