= +23 3 3+ = −+ −  =A CA B A BAC +  − A) 5 3 5 3( )+ − B) ( )+ C)  3 35 3 5 3C D C DBD B D

2) Cho ^{a c}

b = d . Chứng minh rằng :

= +

2

3

3

3

+ = −

+ −

  =

a c

a b a b

ac

 +  −

a) ^{5 3 5 3}

( )

+ − b) ( )

+ c)

 

3

3

5 3 5 3

c d c d

bd b d