Bonjour. Pour les questions 1, 6, 7 et 8, on utilise l'identité : [tex]a^2-b^2=(a+b)(a-b)[/tex].
[tex]A = 16x^2-25\\A = (4x)^2-5^2\\A = (4x+5)(4x-5)\\\\A = 3x+9\\A = 3 \times x + 3 \times 3\\A = 3(x+3)\\\\B = 12x+18y\\B = 6 \times 2x + 6 \times 3y\\B = 6(2x+3y)\\\\C = x^2-5x\\C = x \times x - 5 \times x\\C = x(x-5)[/tex]
[tex]D = 7x-7\\D = 7 \times x - 7 \times 1\\D = 7(x-1)\\\\E = x^2-49\\E = x^2-7^2\\E = (x+7)(x-7)\\\\F = 81-25x^2\\F = 9^2 - (5x)^2\\F = (9+5x)(9-5x)\\\\G = 9x^2-36\\G = (3x)^2-6^2\\G = (3x+6)(3x-6)[/tex]
Bonne journée !
