1: \(P=\dfrac{x\sqrt{x}-3-2\left(\sqrt{x}-3\right)^2-\left(\sqrt{x}+3\right)\left(\sqrt{x}+1\right)}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{x\sqrt{x}-3-2x+12\sqrt{x}-18-x-4\sqrt{x}-3}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{x\sqrt{x}-3x+8\sqrt{x}-24}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+1\right)}=\dfrac{x+8}{\sqrt{x}+1}\)
2: P nguyên
=>x-1+9 chia hết cho căn x+1
=>căn x+1 thuộc {1;-1;3;-3;9;-9}
=>căn x thuộc {0;2;8}
=>x thuộc {0;4;64}
3: P=4
=>x+8=4căn x+4
=>x-4căn x+4=0
=>(căn x-2)^2=0
=>căn x-2=0
=>căn x=2
=>x=4
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