\(a.\left(3x-2\right)^2+\left(3x+2\right)^2-2\left(\left(3x-2\right)\left(3x+2\right)\right)\\=9x^2-12x+4+9x^2+12x+4-18x^2+8\\ =18x^2+8-18x^2+8\\ =16\)
a) (3x-2)2 + (3x+2)2 -2(3x-2)(3x+2)
=(3x-2)2
-2((3x-2)(3x+2)
+ (3x+2)2
=[(3x-2)-(3x+2)]2
=(3x-2-3x-2)
=-42
=8
b)(x-5)(x+5)-(x-6)(x-4)
=x2-52-(x2-4x-6x+24)
=x2-25-x2+10x-24
=10x-49
c) đề sai , bạn xem lại chỗ 2(3x-1)(3x+2)