`***`Lời giải`***`
`\frac{x^4-2x^3+2x-1}{x^2-1} `
`=\frac{x^4-x^3-x^3+x^2-x^2+x+x-1}{x^2-1} `
`=\frac{(x^4-x^3)+(-x^3+x^2)+(-x^2+x)+x-1}{x^2-1} `
`=\frac{x^3(x-1)-x^2(x-1)-x(x-1)+(x-1)}{x^2-1} `
`=\frac{(x-1)(x^3-x^2-x+1)}{x^2-1} `
`=\frac{(x-1)[x^2(x-1)-(x-1)]}{x^2-1} `
`=\frac{(x-1)(x-1)(x^2-1)}{x^2-1} `
`=(x-1)^2`