ĐKXĐ : \(2x-x^2-3\ne0\Rightarrow-x^2+2x-3\ne0\)
\(\Rightarrow-\left(x^2-2x+3\right)\ne0\Rightarrow x^2-2.x+1+2\ne0\)
\(\Rightarrow\left(x-1\right)^2+2\ne0\)
VÌ \(\left(x-1\right)^2\ge0\) dấu = khi x=1
\(2>0\)
\(\Rightarrow\left(x-1\right)^2+2>0\)
\(\Rightarrow\left(x-1\right)^2+2\ne0\) luôn đúng
\(\Rightarrow2x-x^2-3\ne0\) luôn đúng
\(\Rightarrow\text{Đ}K\text{X}\text{Đ}:x\in R\)
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