Mình chỉ phân tích thôi, bạn tự làm tiếp nhé.
1) f(x) = x³ - 9x² + 16x + 26
= (x³ - 10x² + 25x) + (x² - 10x + 25) + (x + 1)
= x(x² - 10x + 25) + (x² - 10x + 25) + (x + 1)
= (x + 1)(x² - 10x + 25) + (x + 1)
= (x + 1)(x - 5)² + (x + 1)
2) A(x) = 2x^4 + x ³ - 22x ² + 5x - 41
= (2x^4 - 18x²) + (x³ - 9x) - (4x² - 36) + (14x + 87)
= 2x²(x² - 9) + x(x² - 9) - 4(x² - 9) + (14x + 87)
= (x² - 9)(2x² + x - 4) + (14x + 87)
3) P(x) = x³ - 4x² - 13x +31
= (x³ - 7x² + 10x) + (3x² - 21x + 30) + (1 - 2x)
= x(x² - 7x +10) +3(x² - 7x + 10) + (1 - 2x)
= (x + 3)(x² - 7x + 10) + (1 - 2x)