Toán Lớp 6: Chứng minh bảy hằng đẳng thức Đây k phải xả điểm ? Đặt lần 3 r đấy

Question

Toán Lớp 6:  Chứng minh bảy hằng đẳng thức  Đây k phải xả điểm ? Đặt lần 3 r đấy

khanhlanchau · Answer

Giải đáp+Lời giải và giải thích chi tiết:   +) a&sup2;+2ab+b&sup2;=a&sup2;+ab+ab+b&sup2;   =a(a+b)+b(a+b)=(a+b)(a+b)=(a+b)&sup2;   +) a&sup2;-2ab+b&sup2;=a&sup2;-ab-ab+b&sup2;   =a(a-b)-b(a-b)=(a-b)(a-b)=(a-b)&sup2;   +) (a-b)(a+b)=a&sup2;+ab-ab-b&sup2;=a&sup2;-b&sup2;   +) a&sup3;+3a&sup2;b+3ab&sup2;+b&sup3;=a(a&sup2;+2ab+b&sup2;)+b(a&sup2;+2ab&sup2;+b&sup2;)   =(a+b)(a&sup2;+2ab+b&sup2;)=(a+b)(a+b)&sup2;=(a+b)&sup3;   +) a&sup3;-3a&sup2;b+3ab&sup2;-b&sup3;=a(a&sup2;-2ab+b&sup2;)-b(a&sup2;-2ab&sup2;+b&sup2;)   =(a-b)(a&sup2;-2ab+b&sup2;)=(a-b)(a-b)&sup2;=(a-b)&sup3;   +) (a+b)(a&sup2;-ab+b&sup2;)=a&sup3;-a&sup2;b+ab&sup2;+a&sup2;b-ab&sup2;+b&sup3;   =a&sup3;+b&sup3;   +) (a-b)(a&sup2;+ab+b&sup2;)=a&sup3;+a&sup2;b+ab&sup2;-a&sup2;b-ab&sup2;-b&sup3;   =a&sup3;-b&sup3;