Rút gọn phân thức sau:
x^3 + 2x^2 - x - 2
--------------------------
x^3 - 3x + 2
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\(=\frac{\left(x^4-x^3\right)-\left(x-1\right)}{\left(x^4+x^3+x^2\right)+\left(2x^2+2x+2\right)}=\frac{x^3.\left(x-1\right)-\left(x-1\right)}{x^2\left(x^2+x+1\right)+2\left(x^2+x+1\right)}\)
\(=\frac{\left(x^3-1\right).\left(x-1\right)}{\left(x^2+2\right)\left(x^2+x+1\right)}=\frac{\left(x-1\right)^2.\left(x^2+x+1\right)}{\left(x^2+2\right)\left(x^2+x+1\right)}=\frac{\left(x-1\right)^2}{x^2+2}\)
\(\frac{2\left(x-2\right)\left(x-3\right)}{\left(3x^2-27\right)\left(x-2\right)}=\frac{2\left(x-2\right)\left(x-3\right)}{\left(x-2\right)3\left(x-3\right)\left(x+3\right)}=\frac{2}{3\left(x+3\right)}\)
ĐKXĐ: \(x\ne1;x\ne-\dfrac{3}{2}\)
Ta có: \(\dfrac{3x^3-7x^2+5x-1}{2x^3-x^2-4x+3}=\dfrac{\left(x-1\right)^2\left(3x-1\right)}{\left(x-1\right)^2\left(2x+3\right)}=\dfrac{3x-1}{2x+3}\)
a: \(=\dfrac{3\left(x-2\right)}{\left(x-2\right)^3}=\dfrac{3}{\left(x-2\right)^2}\)
b: \(=\dfrac{x^2\left(x+2\right)}{\left(x+2\right)^3}=\dfrac{x^2}{\left(x+2\right)^2}\)
\(x^3+2x^2-x-2\)
\(=x^3+3x^2+2x-1x^2-3x-2\)
\(=x\left(x^2+3x+2\right)-1\left(x^2+3x+2\right)\)
\(=\left(x-1\right)\left(x^2+3x+2\right)\)
\(=\left(x-1\right)\left(x^2+x+2x+2\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(x+2\right)\)
\(x^3+3x+2\)
\(=x^3+2x^2-2x^2-4x+x+2\)
\(=\left(x+2\right)x^2-2\left(x^2+2x\right)+x+2\)
\(=\left(x+2\right)x^2-2\left(x^2+2x\right)1\left(x+2\right)\)
\(=\left(x^2-2x+1\right)\left(x+2\right)\)
\(=\left(x-1\right)^2\left(x+2\right)\)