Bjr,
[tex]A = (2x+1)^2\\\text{formule: } (a+b)^2 = a^2+2ab+b^2\\A = (2x)^2+2\times 2x \times 1 + (1)^2 \\A = 4x^2+4x+1\\\\B = 3(5-4x)\\B = 3\times 5 + 3\times(-4x)\\B = 15 -12x = -12x+15\\\\C = (4x-5)(4x+5)\\\text{formule: }(a-b)(a+b) = a^2-b^2\\C = (4x)^2-(5)^2\\C = 16x^2 -25\\\\D = (-3x+1)(2-x)\\D = -3x\times2-(-3x)\times x+1\times 2 -1\times x\\D = -6x+3x^2+2-x\\D = 3x^2-7x+2\\\\E= (7-3x)^2\\\text{formule: }(a-b)^2 = a^2-2ab+b^2\\E = (7)^2 - 2\times 7 \times 3x + (3x)^2\\E = 49 - 42x + 9x^2\\E = 9x^2 -42x + 49[/tex]
Bonne journée.
