Question

\(\dfrac{x^3+x^2-2x-20}{x^2-4}-\dfrac{5}{x+2}+\dfrac{3}{x-2}\)

Answer 1

\(\dfrac{x^3+x^2-2x-20}{x^2-4}-\dfrac{5}{x+2}+\dfrac{3}{x-2}\)

\(=\dfrac{x^3+x^2-2x-20-5\left(x-2\right)+3\left(x+2\right)}{\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{x^3+x^2-2x-20-5x+10+3x+6}{\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{x^3+x^2-4x-4}{\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{x^2\left(x+1\right)-4\left(x+1\right)}{\left(x-2\right)\left(x+2\right)}\)

\(=\dfrac{\left(x-2\right)\left(x+2\right)\left(x+1\right)}{\left(x-2\right)\left(x+2\right)}\)

\(=x+1\)

Answer 2

đề đâu?? tính hay tìm x, phải ghi rõ chứ