bạn ơi câu hỏi là cho đa thứ hay tim x vậy.Cho mink xin đề
\(\frac{x^4-3x^2+1}{x^4-x^2-2x-1}=\frac{x^4-x^3-x^2+x^3-x^2-x-x^2+x+1}{\left(x^2\right)^2-\left(x^2+2x+1\right)}\)
\(=\frac{x^2.\left(x^2-x-1\right)+x\left(x^2-x-1\right)-\left(x^2-x-1\right)}{\left(x^2\right)^2-\left(x+1\right)^2}\)
\(=\frac{\left(x^2-x-1\right)\left(x^2+x-1\right)}{\left[x^2-\left(x+1\right)\right]\left[x^2+\left(x+1\right)\right]}\)
\(=\frac{\left(x^2-x-1\right)\left(x^2+x-1\right)}{\left(x^2-x-1\right)\left(x^2+x+1\right)}\)
\(=\frac{x^2+x-1}{x^2+x+1}\)