Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(a\left(b^2+c^2\right)+b\left(c^2+a^2\right)+c\left(a^2+b^2\right)+2abc\)
\(=ab^2+ac^2+bc^2+ba^2+ca^2+cb^2+2abc\)
\(=\left(ab^2+ba^2\right)+\left(ac^2+bc^2\right)+\left(abc+b^2c\right)+\left(ca^2+abc\right)\)
\(=ab\left(a+b\right)+c^2\left(a+b\right)+bc\left(a+b\right)+ac\left(a+b\right)\)
\(=\left(a+b\right)\left(ab+c^2+bc+ca\right)\)
\(=\left(a+b\right)\left[\left(ab+bc\right)+\left(c^2+ac\right)\right]\)
\(=\left(a+b\right)\left[b\left(a+c\right)+c\left(a+c\right)\right]\)
\(=\left(a+b\right)\left(b+c\right)\left(a+c\right)\)
\(x^3+y^3+z^3-3xyz\)
\(=\left(x+y\right)^3-3xy\left(x+y\right)+z^3-3xyz\)
\(=\left(x+y+z\right)\left[\left(x+y\right)^2-z\left(x+y\right)+z^2\right]-3xy\left(x+y+z\right)\)
\(=\left(x+y+z\right)\left(x^2+y^2+z^2+xy+yz+zx\right)\)
\(\Leftrightarrow ab^2+ac^2-bc^2-a^2c+ca^2+cb^2-abc-abc\)=\(ab\left(b-a\right)-ac\left(b-a\right)-c^2\left(b-a\right)+bc\left(b-a\right)\)
=\(\left(b-a\right)\left(ab-ac-c^2+bc\right)=\left(b-a\right)\left[a\left(b-c\right)+c\left(b-c\right)\right]=\left(b-a\right)\left(b-c\right)\left(a+c\right)\)
\(a.\left(b^2+c^2+bc\right)+b.\left(c^2+a^2+ac\right)+c.\left(a^2+b^2+ab\right)\)
\(=ab^2+ac^2+abc+bc^2+ba^2+bac+ca^2+cb^2+cab\)
\(=\left(ab^2+ba^2+abc\right)+\left(ac^2+ca^2+bac\right)+\left(bc^2+cb^2+cab\right)\)
\(=ab.\left(b+a+c\right)+ac.\left(c+a+b\right)+bc.\left(c+b+a\right)\)
\(=\left(a+b+c\right).\left(ab+ac+bc\right)\)
(Nhớ click cho mình với nhoa!)