1) -12ab
2) a²+2ab+b²-2bc+c²-2ac
Объяснение:
1) (3a-b)²-(3a+b)²=9a²-6ab+b²-(9a²+6ab+b²)=9a²-6ab+b²-9a²-6ab-b²=-12ab
2) (a+b-c)²=(a+b-c)*(a+b-c)=a²+ab-ac+ab+b²-bc-ac-bc+c²=a²+2ab+b²-2bc+c²-2ac
1) -12ab
2) a²+2ab+b²-2bc+c²-2ac
Объяснение:
1) (3a-b)²-(3a+b)²=9a²-6ab+b²-(9a²+6ab+b²)=9a²-6ab+b²-9a²-6ab-b²=-12ab
2) (a+b-c)²=(a+b-c)*(a+b-c)=a²+ab-ac+ab+b²-bc-ac-bc+c²=a²+2ab+b²-2bc+c²-2ac