\(f,x^4+3x^3-x-3=0\)
\(\Rightarrow x^3\left(x+3\right)-\left(x+3\right)=0\)
\(\Rightarrow\left(x^3-1\right)\left(x+3\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x^3-1=0\\x+3=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=1\\x=-3\end{matrix}\right.\)
Vậy \(x\in\left\{1;-3\right\}\)
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\(g,x^2-4x-12=0\)
\(\Rightarrow x^2-6x+2x-12=0\)
\(\Rightarrow x\left(x-6\right)+2\left(x-6\right)=0\)
\(\Rightarrow\left(x-6\right)\left(x+2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-6=0\\x+2=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=6\\x=-2\end{matrix}\right.\)
Vậy \(x\in\left\{6;-2\right\}\)
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\(h,x^2+3x-10=0\)
\(\Rightarrow x^2-2x+5x-10=0\)
\(\Rightarrow x\left(x-2\right)+5\left(x-2\right)=0\)
\(\Rightarrow\left(x+5\right)\left(x-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+5=0\\x-2=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)
Vậy \(x\in\left\{-5;2\right\}\)
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\(i,2x^2-x=6\)
\(\Rightarrow2x^2-x-6=0\)
\(\Rightarrow2x^2-4x+3x-6=0\)
\(\Rightarrow2x\left(x-2\right)+3\left(x-2\right)=0\)
\(\Rightarrow\left(2x+3\right)\left(x-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2x+3=0\\x-2=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{-3}{2}\\x=2\end{matrix}\right.\)
Vậy \(x\in\left\{\dfrac{-3}{2};2\right\}\)
