a) Ta có : ( -54 ) . ( 1-234 ) - 234 . 54
= ( -54 ) . ( -233 ) - 234 . 54
= 54 . 233 - 234 . 54
= 54. ( 233 - 234 )
= 54 . ( -1 )
= -54
b) Ta có : ( - 4 ) . ( + 125 ) . ( -25 ) . ( - 6 ) . ( -8)
= [ ( -4 ) .( -25 )] . [ ( 125 . ( - 8) ] . ( -6 )
= 100 . ( -1000 ) . ( - 6 )
= ( - 100000 ) . ( -6 )
= 600000