Bonjour,
10)
[tex]\frac{-28}{49} = -\frac{7\times 4}{7\times 7} = -\frac{4}{7}\\\\\frac{84}{-48} = -\frac{7\times12}{4\times 12} = -\frac{7}{4}[/tex]
Ces nombres sont inverses.
11)
[tex]\frac{-39}{52} = - \frac{13\times 3}{13\times 4} = -\frac{3}{4}\\\\\frac{24}{32} = \frac{8\times 3}{8\times 4} = \frac{3}{4}[/tex]
Ces nombres sont opposés.
12) (2b - 5)(6 + b) = 12b + 2b² - 30 - 5b = 2b² + 7b - 30
13) (5x + 2)(7x - 8) = 35x² - 40x + 14x - 16 = 35x² - 26x - 16
14) (x + 11)² = x² + 22x + 121 #(a + b)² = a² + 2ab + b²
15) (4x - 6)² = 16x² - 48x + 36 #(a - b)² = a² - 2ab + b²
16) (5 - x)(5 + x) = 25 - x² #(a - b)(a + b) = a² - b²
17)
[tex]\left(3x + \frac{2}{5}\right)^2 = 9x^2 + \frac{12}{5}x + \frac{4}{25}[/tex]
18) 3x(5x + 2) + 7(5x + 2) = (5x + 2)(3x + 7)
19) x² - 81 = x² - 9² = (x + 9)(x - 9)
20) (2x - 1)(x - 2) - 3x(x - 2) = (x - 2)(2x - 1 - 3x) = (x - 2)(- x - 1) = -(x - 2)(x + 1)
21) 100x² - 64 = (10x)² - 8² = (10x + 8)(10x - 8)
Bonee journée.
