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7 tháng 10 2018

ab(a+b) + bc(b+c) + ca(c+a) = a^2b + ab^2 + b^2c + bc^2 + ca(c+a) + 2abc 
= ab^2 + b^2c + a^2b + bc^2 + 2abc + ca(c+a) 
=b^2(a+c) + b(a^2 + c^2 + 2ac) + ca(c+a) 
=b^2(a+c) + b(a+c)^2 + ca(c+a) 
=(c+a)[b^2 + b(a+c) + ca] 
=(c+a)[b^2 + ab + bc + ca] 
=(c+a)[b(b+a) + c(b+a)] 
=(c+a)(b+c)(b+a) 

13 tháng 7 2017

\(ab\left(a+b\right)+bc\left(b+c\right)+ac\left(a+c\right)+2abc\)

\(=ab\left(a+b\right)+b^2c+bc^2+a^2c+ac^2+2abc\)

\(=ab\left(a+b\right)+\left(ac^2+bc^2\right)+\left(a^2c+2abc+b^2c\right)\)

\(=ab\left(a+b\right)+c^2\left(a+b\right)+c\left(a^2+2ab+b^2\right)\)

\(=ab\left(a+b\right)+c^2\left(a+b\right)+c\left(a+b\right)^2\)

\(=ab\left(a+b\right)+c^2\left(a+b\right)+\left(ac+bc\right)\left(a+b\right)\)

\(=\left(a+b\right)\left(ab+c^2+ac+bc\right)\)

\(=\left(a+b\right)\left[\left(ab+ac\right)+\left(c^2+bc\right)\right]\)

\(=\left(a+b\right)\left[a\left(b+c\right)+c\left(b+c\right)\right]\)

\(=\left(a+b\right)\left(b+c\right)\left(c+a\right)\)

\(ab\left(a+b\right)+bc\left(b+c\right)+ca\left(c+a\right)+2abc\)

\(=\)\(ab\left(a+b\right)+bc\left(a+b+c-a\right)+ca\left(c+a\right)+2abc\)

\(=\)\(ab\left(a+b\right)+bc\left(a+b\right)+bc\left(c-a\right)+ca\left(c+a\right)+2abc\)

\(=\)\(\left(a+b\right)\left(ab+bc\right)+bc\left(c-a\right)+ca\left(c+a\right)+2abc\)

\(=\)\(b\left(a+b\right)\left(c+a\right)+bc\left(c-a\right)+ca\left(c+a\right)+2abc\)

\(=\)\(b\left(ac+a^2+bc+ab\right)+b\left(c^2-ca\right)+ca\left(c+a\right)+2abc\)

\(=\)\(b\left(ca+a^2+bc+ab+c^2-ca\right)+ca\left(c+a\right)+2abc\)

\(=\)\(b\left(a^2+ab+bc+c^2\right)+ca\left(c+a\right)+2abc\)

\(=\)\(b\left(a^2+2ca+c^2+ab+bc\right)+ca\left(c+a\right)\)

\(=\)\(b\left[\left(c+a\right)^2+b\left(c+a\right)\right]+ca\left(c+a\right)\)

\(=\)\(b\left(c+a\right)\left(a+b+c\right)+ca\left(c+a\right)\)

\(=\)\(\left(c+a\right)\left(ab+b^2+bc+ca\right)\)

\(=\)\(\left(c+a\right)\left[b\left(a+b\right)+c\left(a+b\right)\right]\)

\(=\)\(\left(a+b\right)\left(b+c\right)\left(c+a\right)\)

...

4 tháng 1 2019

cách này ngắn hơn nè:

\(ab.\left(a+b\right)+bc.\left(b+c\right)+ac.\left(a+c\right)+2abc\)

\(=a^2b+ab^2+b^2c+bc^2+a^2c+ac^2+abc+abc\)

\(=\left(abc+ac^2\right)+\left(abc+b^2c\right)+\left(a^2b+ab^2\right)+\left(c^2a+c^2b\right)\)

\(=ac.\left(a+b\right)+bc.\left(a+b\right)+ab.\left(a+b\right)+c^2.\left(a+b\right)\)

\(=\left(a+b\right).\left(ac+bc+ab+c^2\right)\)

\(=\left(a+b\right).\left[c\left(a+c\right)+b.\left(a+c\right)\right]=\left(a+b\right).\left(c+b\right).\left(a+c\right)\)

19 tháng 9 2018

\(x^3+y^3+z^3-3xyz\)

\(=\left(x+y\right)^3-3xy\left(x+y\right)+z^3-3xyz\)

\(=\left(x+y+z\right)\left[\left(x+y\right)^2-z\left(x+y\right)+z^2\right]-3xy\left(x+y+z\right)\)

\(=\left(x+y+z\right)\left(x^2+y^2+z^2+xy+yz+zx\right)\)

13 tháng 10 2016

d) (b+c)(b+a)(c-a)

c) (b-1)(ac+1-a-c)

thông cảm 2 câu đầu chưa nghĩ ra 

19 tháng 10 2016

cho mình k mình giúp

19 tháng 10 2016

- Giúp với ạ