$(1)-(2)\rightarrow (x-y)(x^2y+x^3-5)=0$$+)x=y.$ Từ $(1)\rightarrow x^4+5x-6=0\rightarrow ...........$
$+)x^2y+x^3=5(\bigstar)$
Ta có: $3(x^2y+x^2-5)-(x^2y^2+5x-6)=0$
$\Leftrightarrow x^2(y-\frac{3}{2})^2$$-3x^3-\frac{9}{4}x^2+5x+9=0$
Mà $g(x)$$>0$$\forall x\leq \frac{6}{5}$
$\rightarrow (\bigstar)$ vô nghiệm.
$\rightarrow ................KL:..............$
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