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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 9: tim x,y,z thoa man dieu kien √x + √(y-1) + √(z-2) = 1/2(x+y+z)

Toán Lớp 9: tim x,y,z thoa man dieu kien √x + √(y-1) + √(z-2) = 1/2(x+y+z)

Comments ( 1 )

  1. $\begin{array}{l} \sqrt x  + \sqrt {y – 1}  + \sqrt {z – 2}  = \frac{1}{2}\left( {x + y + z} \right)\\  \Leftrightarrow 2\sqrt x  + 2\sqrt {y – 1}  + 2\sqrt {z – 2}  = x + y + z\\  \Leftrightarrow x – 2\sqrt x  + 1 + y – 1 – 2\sqrt {y – 1}  + 1 + z – 2 + 2\sqrt {z – 2}  + 1 = 0\\  \Leftrightarrow {\left( {\sqrt x  – 1} \right)^2} + \left( {\sqrt {y – 1}  – 1} \right) + {\left( {\sqrt {z – 2}  – 1} \right)^2} = 0\\  \Leftrightarrow \left\{ \begin{array}{l} \sqrt x  – 1 = 0\\ \sqrt {y – 1}  – 1 = 0\\ \sqrt {z – 2}  – 1 = 0 \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} x = 1\\ y = 2\\ z = 3 \end{array} \right. \end{array}$

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222-9+11+12:2*14+14 = ? ( )

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