Đáp án:
Giải thích các bước giải:
1) (a+b)²=a²+2ab+b²
VP: a²+2ab+b²=a²+ab+ab+b²=a(a+b)+b(a+b)=(a+b)(a+b)=(a+b)²=VT
2) (a-b)²=a²-2ab+b²
VP: a²-2ab+b²=a²-ab-ab+b²=a(a-b)-b(a-b)=(a-b)(a-b)=(a-b)²=VT
3) (a-b)(a+b)=a²-b²
VT: (a-b)(a+b)=a²+ab-ab-b²=a²-b²=VP
4) (a+b)³=a³+3a²b+3ab²+b³
VT:(a+b)³=(a+b)²(a+b)=(a²+2ab+b²)(a+b)=a³+a²b+2a²b+2ab²+ab²+b³=a³+3a²b+3ab²+b³=VP
5) (a-b)³=a³-3a²b+3ab²-b³
VT: (a-b)³=(a-b)²(a-b)=(a²-2ab+b²)(a-b)=a³-a²b-2a²b+2ab²+ab²-b³=a³-3a²b+3ab²-b³=VP
6) (a+b)(a²-ab+b²)=a³+b³
VT: (a+b)(a²-ab+b²)=a³-a²b+ab²+a²b-ab²+b³=a³+b³=VP
7) (a-b)(a²+ab+b²)=a³-b³
VT: (a-b)(a²+ab+b²)=a³+a²b+ab²-a²b-ab²-b³=a³-b³=VP