Réponse:
4.a)4x²+12x+9
b)x²-2x+1
c)-x²+9
5.a)(-6x+6)(12x-2)
b)(x-4)(x+6)
c)(2x-5)²
Explications étape par étape:
4.a)(2x+3)²
=(2x)²+2×2x×3+3²
=4x²+12x+9
b)(x-1)²
=x²-2×x×1+1²
=x²-2x+1
c)(3-x)(3+x)
=3²-x²
=-x²+9
5.a)(3x+2)²-(9x-4)²
=(3x+2-(9x-4))(3x+2+9x-4)
=(-6x+6)(12x-2)
b)(x+1)²-25
=(x+1)²-5²
=(x+1-5)(x+1+5)
=(x-4)(x+6)
c)4x²-20x+25
=(2x)²-2×2x×5+5²
=(2x-5)²
