Question

Tìm x,thỏa mãn

Answer 1

5) \(25\left(x+1\right)^4-26\left(x+1\right)^2+1=0\)

\(\Rightarrow\left[{}\begin{matrix}\left(x+1\right)^2=1\\\left(x+1\right)^2=\dfrac{1}{25}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x+1=1\\x+1=-1\\x+1=\dfrac{1}{5}\\x+1=-\dfrac{1}{5}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-2\\x=-\dfrac{6}{5}\\x=-\dfrac{4}{5}\end{matrix}\right.\)

6) \(x^4+x^3+2x-4=0\)

\(\Rightarrow\left(x^2+x-2\right)\left(x^2+2\right)=0\)

\(\Leftrightarrow x^2+x-2=0\) do \(x^2+2>0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-2\end{matrix}\right.\)