Phân tích đa thức

a) A = x (2x + 1) − x²(x + 2) + (x² − x + 3)
b) B = x(x³ + 2x² − 3x + 2) − (x² + 2x)x² + 3x(x − 1) + 1 −
c) C = 3ay² (4x² -2y) - 6y (2x³y + 1) + 6(ry² + y − 3)
d) D = 3x(x - 5y) + (y – 5x)(-3y) - 1-3(x² - y²
)