a) ĐKXĐ của B là: \(x\ne0;x\ne-2\)
b) \(B=\dfrac{\left(x+2\right)^2}{x}\cdot\left(1-\dfrac{x^2}{x+2}\right)-\dfrac{x^2+6x+4}{x}\)
\(B=\dfrac{\left(x+2\right)^2}{x}\cdot\dfrac{\left(x+2\right)-x^2}{x+2}-\dfrac{x^2+6x+4}{x}\)
\(B=\dfrac{\left(x+2\right)^2\left[\left(x+2\right)-x^2\right]}{x\left(x+2\right)}-\dfrac{x^2+6x+4}{x}\)
\(B=\dfrac{\left(x+2\right)\left[\left(x+2\right)-x^2\right]}{x}-\dfrac{x^2+6x+4}{x}\)
\(B=\dfrac{\left(x+2\right)^2-x^2\left(x+2\right)-\left(x^2+6x+4\right)}{x}\)
\(B=\dfrac{x^2+4x+4-x^3-2x^2-x^2-6x-4}{x}\)
\(B=\dfrac{-x^3-2x^2-2x}{x}\)
\(B=\dfrac{-x\left(x^2+2x+2\right)}{x}\)
\(B=-x^2-2x-2\)
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