Bài lm nek
Nhớ vote cho mk 5 sao nhá 😉
Câu 1.
A = (2x - 3)² - (3x - 2)(x + 3)
-> A = (4x² - 12x + 9) - [ 3x (x + 3) - 2 (x + 3)]
-> A = (4x² - 12x + 9) - (3x² + 9x - 2x - 6)
-> A = 4x² - 12x + 9 - 3x² - 9x + 2x + 6
-> A = (4x² - 3x²) + (2x - 12x - 9x) + (9 + 6)
-> A = x² - 19x + 15
Câu 2.
B = (2 - 3x)² - 3 (2x - 3)(2x + 4)
-> B = (4 - 12x + 9x²) - 3 [ 2x (2x + 4) - 3 (2x + 4)]
-> B = (4 - 12x + 9x²) - 3 (4x² + 8x - 6x - 12)
-> B = (4 - 12x + 9x²) - (12x² + 24x - 18x - 36)
-> B = 4 - 12x + 9x² - 12x² - 24x + 18x + 36
-> B = (4 + 36) + (18x - 12x - 24x) + (9x² - 12x²)
-> B = 40 - 18x - 3x²
Câu 3.
C = (3x - 4)² - (2x - 5)(5x - 2)
-> C = (9x² - 24x + 16) - [ 2x (5x - 2) - 5 (5x - 2)]
-> C = (9x² - 24x + 16) - (10x² - 4x - 25x + 10)
-> C = 9x² - 24x + 16 - 10x² + 4x + 25x - 10
-> C = (16 - 10) + (4x + 25x - 24x) + (9x² - 10x²)
-> C = 6 + 5x - x²
Câu 4.
D = (x - 3)³ - x (x + 2)(x - 2)
-> D = (x³ - 9x² + 27x - 27) - x (x² - 4)
-> D = (x³ - 9x² + 27x - 27) - (x³ - 4x)
-> D = x³ - 9x² + 27x - 27 - x³ + 4x
-> D = (x³ - x³) - 9x² + (27x + 4x) - 27
-> D = -9x² + 31x - 27
