Bonjour,
Exercice 1 :
A. (-3x + 1)(-4x + 3) = 12x² - 9x - 4x + 3 = 12x² - 13x + 3
(1 - 3x)(-4x + 3) = -4x + 3 + 12x² - 9x = 12x² - 13x + 3
→ Egalité vraie
B. (4 - 5x)(3x - 5)x = x(12x - 20 - 15x² + 25x) = -15x³ + 37x² - 20x
-x (5 - 3x)(5x - 4) = (-5x + 3x²)(5x - 4) = -20x² + 20x + 15x³ - 12x² = 15x³ - 32x² + 20x
→ Egalité fausse
C. (-3x + x²)(-1 + 2x) = 3x - 6x² - x² + 2x³ = 2x³ - 7x² + 3x
(-x + 2x²)(-3 + x) = 3x - x² - 6x² + 2x³ = 2x³ - 7x² + 3x
→ Egalité vraie
D. (4x - 1)(5 + 2x)x = x(20x + 8x² - 5 - 2x) = 8x³ + 18x² - 5x
(4x - 1) * (-x) (5 + 2x) = (-4x² + x)(5 + 2x) = -20x² - 8x³ + 5x + 2x² = -8x³ - 18x² + 5x
→ Egalité fausse
Exercice 2 :
(5/6)/(y - 7/3) = 3/5
y - 7/3 = (5/6)/(3/5)
y - 7/3 = 5/6 * 5/3
y - 7/3 = 25/18
y = 25/18 + 7/3
y = 25/18 + 42/18
y = 67/18
