Question

Tìm x: (x²+1)(x-2) + 2x = 4

Answer 1

\(\left(x^2+1\right).\left(x-2\right)+2x=4\)
\(\Rightarrow\left(x^2+1\right).\left(x-2\right)+2x-4=0\)
\(\Rightarrow\left(x^2+1\right).\left(x-2\right)+2.\left(x-2\right)=0\)
\(\Rightarrow\left(x^2+1+2\right).\left(x-2\right)=0\)
\(\Rightarrow\left(x^2+3\right).\left(x-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x^2+3=0\\x-2=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x^2=3\left(loai,dox^2\ge0\forall x\right)\\x=2\end{matrix}\right.\)
Vậy x =2