Bonsoir,
1)
a) (x + 5)² + 2 (2x - 1) (x + 1)
= x² + 10x + 25 + 2 (2x²+ 2x - x - 1)
= x² + 10x + 25 + 4x² + 4x - 2x - 2
= x² + 4x² + 10x + 4x - 2x + 25 - 2
= 5x² + 12x + 23
b) 4x + x [3 - x (7 - x)] - 2x [4x - (x - 2)]
= 4x + x (3 - 7x + x²) - 2x (4x - x + 2)
= 4x + 3x - 7x² + x³ - 8x² + 2x² - 4x
= x³ - 7x² - 8x² + 2x² + 4x - 4x + 3x
= x³ - 13x² + 3x
c) (x - 9) (3x + 8)²
= (x - 9) (9x² + 48x + 64)
= 9x³ + 48x² + 64x - 81x² - 432x - 576
= 9x³ - 33x² - 368x - 576
2)
a) x² - 81 - 7 (x + 9)
= (x - 9 - 7) (x + 9)
= (x - 16) (x + 9)
b) 36x² - 12ax + a²
?
c) (- x + 1) (2x + 1) + (- 2x - 1) (x - 10)
= (- x + 1 - x - 10) (2x + 1)
= (-2x + 11) (2x + 1)
