A)Faux
(5-2y)^2
=(5×5)-(5×2y)+(2y×2y)-(2y×5)
=25-10y+4y^2-10y
=4y^2-20y+25
B)Vrai
(X-7)^2
=(x×x)-(x×7)+(7×7)-(7×x)
=x^2-7x+49-7x
=x^2-14x+49
(7-x)^2
=(7×7)-(7×x)+(x×x)-(x×7)
=49-7x+x^2-7x
=x^2-14x+49
C)Faux
(9+3a)(9-3a)
=(9×9)-(9×3a)+(3a×9)-(3a×3a)
=81-27a+27a-9a^2
=-9a^2+81
D)Faux
(X+11)^2
=(x×x)+(x×11)+(11×11)+(11×x)
=x^2+11x+121+11x
=x^2+22x+121
Distributivité
