Gửi bạn Hữu Minh bài 2

Ta co:
b  1; c  1; a  1  0




  2 a  1
b  1  c  1   4(a  1)
Mat _ khac :  b  1  c  1   2(b  1  c  1)  4  2(b  c)



b 1  c 1

2

2

2

2

 4  2(b  c)  4(a  1)  b  c  2a