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Nguyễn Hưng Phát

21/12/2017 at 16:38
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Solve the equation:\(\left\{{}\begin{matrix}32x^3-48x^2+30x+\left(4y-7\right)\sqrt{1-y}=7\\3x+y-3=0\end{matrix}\right.\)




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    Lightning Farron 22/12/2017 at 18:37

    #NOTE:\(e=equation\)

    \(e\left(2\right)\Leftrightarrow y=3-3x\)

    \(\Rightarrow e\left(1\right)\Leftrightarrow32x^3-48x^2+30x+\left(4\left(3-3x\right)-7\right)\sqrt{1-\left(3-3x\right)}=7\)

    \(\Leftrightarrow32x^3-48x^2+30x+\left(5-12x\right)\sqrt{3x-2}=7\)

    \(\Leftrightarrow32x^3-48x^2+10x+6+\left(5-12x\right)\sqrt{3x-2}-\left(-20x+13\right)=0\)

    \(\Leftrightarrow2\left(x-1\right)\left(4x-3\right)\left(4x+1\right)+\dfrac{\left(x-1\right)\left(4x-3\right)\left(108x-73\right)}{\left(5-12x\right)\sqrt{3x-2}-20x+13}=0\)

    \(\Leftrightarrow\left(x-1\right)\left(4x-3\right)\left(2\left(4x+1\right)+\dfrac{\left(108x-73\right)}{\left(5-12x\right)\sqrt{3x-2}-20x+13}\right)=0\)

    See: \(2\left(4x+1\right)+\dfrac{\left(108x-73\right)}{\left(5-12x\right)\sqrt{3x-2}-20x+13}>0\)

    \(\Rightarrow\left[{}\begin{matrix}x-1=0\\4x-3=0\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{3}{4}\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}y=3-3x=3-3\cdot1=0\\y=3-3x=3-3\cdot\dfrac{3}{4}=\dfrac{3}{4}\end{matrix}\right.\)

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    Nguyễn Hưng Phát 22/12/2017 at 21:25

    Lightning Farron:I don't understand

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    Lightning Farron 22/12/2017 at 21:22

    ( ͡° ͜ʖ ͡°) 

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    Nguyễn Hưng Phát 22/12/2017 at 20:57

    Lightning Farron:\(2\left(4x+1\right)+\dfrac{108x-73}{\left(5-12x\right)\sqrt{3x-2}-20x+13}>0\).Why?


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