Đặt \(\left\{{}\begin{matrix}x+1=a\\2x-5=b\end{matrix}\right.\) \(\Rightarrow3x-4=a+b\)
\(a^3+b^3-\left(a+b\right)^3=0\)
\(\Leftrightarrow a^3+b^3-\left[a^3+b^3+3ab\left(a+b\right)\right]=0\)
\(\Leftrightarrow ab\left(a+b\right)=0\Rightarrow\left[{}\begin{matrix}a=0\\b=0\\a+b=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x+1=0\\2x-5=0\\3x-4=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=-1\\x=\frac{5}{2}\\x=\frac{4}{3}\end{matrix}\right.\)
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