bonjour
exercice 6 )))
[tex](5x - 4) {}^{2} = (5x) {}^{2} - 2 \times 5x \times 4 + {4}^{2} = 25 {x}^{2} - 40x + 16[/tex]
[tex](4x + 3 {)}^{2} = (4x) {}^{2} + 2 \times 3 \times 4x + 3 {}^{2} = 16 {x}^{2} + 24x + 9[/tex]
[tex](3x - 7)(3x + 7) = (3x) {}^{2} - 7 {}^{2} = 9 {x}^{2} - 49[/tex]
exercice 7 ))))
x² -6x + 9 = x ² - 2×x×3 + 3² = (x-3)²
x² + 10 x + 25 = x² + 2 ×5×x + 5² = (x+5)²
x²-81 = x² - 9² = (x-9)(x+9)
exercice 8 )))
49x² - 36 = (7x)² - 6² =( 7x+6)(7x-6)
exercice 9))))
[tex]7(2x - 6) + (3x - 4)(2x - 6) = 14x - 42 + 6x {}^{2} - 18x - 8x + 24 = - 12x - 18 + 6x {}^{2} [/tex]
calculer pour x = - 2
-12×-2 - 18 + 6 × (-2)²
= 24 - 18 + 24 = 30
Factoriser
(2x-6)(7+3x-4) = (2x-6)(3+3x) = 2(x-3)3(1+x) = 6(x-3)(1+x)
bonne continuation
