Răspuns :
[3(2x-5)] ² - [2(4x-3)] ² = [3(2x-5) + 2(4x-3)][3(2x-5) - 2(4x-3)]=
=(6x-15 + 8x-6)(6x-15-8x+6)
=(14x-21)(-2x-9)=
= -14 (x-3)(x+9)
=(6x-15 + 8x-6)(6x-15-8x+6)
=(14x-21)(-2x-9)=
= -14 (x-3)(x+9)