a) 2x2y(x2+xy-3y2)= 2x4y + 2x3y2 - 6x2y3b) (2x+1)(x-1)= 2x2 - 2x + x -1= 2x2 -x -1c) (3xy2+6x2y-9xy):3xy= y + 2x - 3d) \(\dfrac{2x+7}{x+1}+\dfrac{x-4}{x+1}\)= \(\dfrac{2x+7+x-4}{x+1}\)= \(\dfrac{3x+3}{x+1}\)= \(\dfrac{3\left(x+1\right)}{x+1}\)= 3e) \(\dfrac{\left(x+2\right)^2}{x-1}:\dfrac{x+2}{3x-3}\)= \(\dfrac{\left(x+2\right)^2}{x-1}.\dfrac{3\left(x-1\right)}{x+2}\)= 3(x+2) = 3x+6f) \(\left(\dfrac{x^2+2x+2}{x+2}-\dfrac{1}{x+2}\right):\dfrac{x-1}{x+2}\)= \(\left(\dfrac{x^2+2x+2-1}{x+2}\right):\dfrac{x-1}{x+2}\)= \(\dfrac{x^2+2x+1}{x+2}.\dfrac{x+2}{x-1}\)= \(\dfrac{\left(x+1\right)^2}{x-1}\)Câu trả lời: a) 2x2y(x2+xy-3y2)= 2x4y + 2x3y2 - 6x2y3b) (2x+1)(x-1)= 2x2 - 2x + x -1= 2x2 -x -1c) (3xy2+6x2y-9xy):3xy= y + 2x - 3d) \(\dfrac{2x+7}{x+1}+\dfrac{x-4}{x+1}\)= \(\dfrac{2x+7+x-4}{x+1}\)= \(\dfrac{3x+3}{x+1}\)= \(\dfrac{3\left(x+1\right)}{x+1}\)= 3e) \(\dfrac{\left(x+2\right)^2}{x-1}:\dfrac{x+2}{3x-3}\)= \(\dfrac{\left(x+2\right)^2}{x-1}.\dfrac{3\left(x-1\right)}{x+2}\)= 3(x+2) = 3x+6f) \(\left(\dfrac{x^2+2x+2}{x+2}-\dfrac{1}{x+2}\right):\dfrac{x-1}{x+2}\)= \(\left(\dfrac{x^2+2x+2-1}{x+2}\right):\dfrac{x-1}{x+2}\)= \(\dfrac{x^2+2x+1}{x+2}.\dfrac{x+2}{x-1}\)= \(\dfrac{\left(x+1\right)^2}{x-1}\)