Tính: d) 4x2y – 2xy2 + 8 – (3x2y + 9xy2 – 12xy + 6).

d) 4x²y – 2xy² + 8 – (3x²y + 9xy² – 12xy + 6).

= 4x²y – 2xy² + 8 – 3x²y – 9xy² + 12xy – 6

= (4x²y – 3x²y) + (– 2xy² – 9xy²) + (8 – 6) + 12xy

= x²y – 11xy² + 2 + 12xy.