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Bonjour

factoriser

a) -(1+3x)^2+4x^2

A = 4x^2 - (1 + 3x)^2

A = a^2 - b^2 = (a - b)(a + b)

A = (2x - 1 - 3x)(2x + 1 + 3x)

A = (-x - 1)(5x + 1)

b) ((x-3)/2)^2-x^2/4

B = 1/4[(x - 3)^2 - x^2]

B = 1/4(x - 3 - x)(x - 3 + x)

B = 1/4(-3)(2x - 3)

B = -3/4(2x - 3)

c) (1-3x)^2 - 3

d) 9x^2+12x+4

D = (3x)^2 + 2 * 3x * 2 + 2^2

D = (3x + 2)^2