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12 tháng 5 2017

Ta có:

\(A=bc\left(a+d\right)\left(b-c\right)-ac\left(b+d\right)\left(a-c\right)+ab\left(c+d\right)\left(a-b\right)\)

\(=bc\left(a+d\right)\left[\left(b-a\right)+\left(a-c\right)\right]-ac\left(a-c\right)\left(b+d\right)+ab\left(c+d\right)\)\(\left(a-b\right)\)

\(=bc\left(a+d\right)\left(a-b\right)+bc\left(a+d\right)\left(a-c\right)-ac\left(b+d\right)\left(a-c\right)\)\(+ab\left(c+d\right)\left(a-b\right)\)

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

\(=b\left(a-b\right).d\left(a-c\right)+c\left(a-c\right).d\left(b-a\right)\)

\(=d\left(a-b\right)\left(a-c\right)\left(b-c\right)\)

14 tháng 9 2016

= a2b + ab- b2c + bc+ a2c - ac2

17 tháng 10 2016

bố éo biết

13 tháng 7 2017

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

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

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

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

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

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

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

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

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

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

13 tháng 8 2018

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

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

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

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

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