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Math Help - can figure out how to do this

  1. #1
    cherrybomb21
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    Unhappy can figure out how to do this

    a+b=4
    ab=7.74

    solve for a and b

    any help would really be appreciated.
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  2. #2
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    earboth's Avatar
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    Quote Originally Posted by cherrybomb21 View Post
    a+b=4
    ab=7.74

    solve for a and b
    Hello,

    a+b=4~\implies~b=4-a . Plug in this term into the 2nd equation:

    a(4-a)=7.74 and solve for a.

    But be careful: This equation has no real solution!
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  3. #3
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    Hello, cherrybomb21!

    Is there a typo?
    . . There are no real solutions.


    Solve for a and b\!:\;\;\begin{array}{ccc}a+b &= & 4\\<br />
ab & =& 7.74\end{array}

    Solve the first equation for b\!:\;\;b \:=\:4-a

    Substitute into the second equation: . a(4-a) \:=\:7.74

    And we have a quadratic equation: . a^2 - 4a + 7.74 \:=\:0

    . . which has complex roots: . \begin{array}{ccc}a & = & 2 \pm i\sqrt{3.74} \\ b & = & 2 \mp i\sqrt{3.74}\end{array}

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