n: ĐKXĐ: x<>0
\(\left(x+\dfrac{1}{x}\right)^2-3\left(x+\dfrac{1}{x}\right)+2=0\)
=>\(\left(x+\dfrac{1}{x}\right)^2-2\left(x+\dfrac{1}{x}\right)-\left(x+\dfrac{1}{x}\right)+2=0\)
=>\(\left(x+\dfrac{1}{x}-2\right)\left(x+\dfrac{1}{x}-1\right)=0\)
=>\(\dfrac{x^2+1-2x}{x}\cdot\dfrac{x^2+1-x}{x}=0\)
=>\(\left(x^2-2x+1\right)\left(x^2-x+1\right)=0\)
=>\(\left(x-1\right)^2\left[\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}\right]=0\)
=>\(\left(x-1\right)^2=0\)
=>x-1=0
=>x=1
p: \(x^4-4x^3+6x^2-4x+1=0\)
=>\(x^4-x^3-3x^3+3x^2+3x^2-3x-x+1=0\)
=>\(x^3\left(x-1\right)-3x^2\left(x-1\right)+3x\left(x-1\right)-\left(x-1\right)=0\)
=>\(\left(x-1\right)\left(x^3-3x^2+3x-1\right)=0\)
=>\(\left(x-1\right)^4=0\)
=>x-1=0
=>x=1
