Rút gọn biểu thức: x(x^2 – y) – x^2(x + y) + xy(x – 1).
Giải thích
Ta có x(x2 – y) – x2(x + y) + xy(x – 1)
= x . x2 – x . y – x2 . x – x2 . y + xy . x – xy . 1
= x3 – xy – x3 – x2y + x2y – xy
= (x3 – x3) + (x2y – x2y) – (xy + xy) = –2xy.
Ta có x(x2 – y) – x2(x + y) + xy(x – 1)
= x . x2 – x . y – x2 . x – x2 . y + xy . x – xy . 1
= x3 – xy – x3 – x2y + x2y – xy
= (x3 – x3) + (x2y – x2y) – (xy + xy) = –2xy.