Question

Tìm x, y, z biết

a) \(\text{x}^{\text{2}}+5\text{y}^{\text{2}}-4xy+6y+9=0\)b) \(2\text{x}^{\text{2}}+4\text{y}^{\text{2}}+\text{z}^{\text{2}}-4xy+4\text{y}^{\text{2}}-2x-2z+5=0 \)

Answer 1

b) \(2x^2+4y^2+z^2-4xy-2x-2z+5=0\)

\(\Leftrightarrow\left(x^2-4xy+4y^2\right)+\left(x^2-2x+1\right)+\left(z^2-2z+1\right)+3=0\)

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