tính nhanh
15.(-24)+(-24).84-24
= 15 . ( - 24 ) +(-24) .84 + ( -24 ) .1
=( 15 + 84 + 1 ) . (-24)
= 100 . ( -24 )
= _2400
thêm
A)27.(-16)+(-16).74+16
B)38.(78-59)-78.(38-59)
C) 74.(32+5)-32.(74+5)
D -17.25+34.26-17.49
15 . (-24) + (-24) . 84 - 24
= [(-24) + 24] . (84 - 24) . 15
= 0 . 60 . 15
= 0 . 15
= 0
a) 27 . (-16) + (-16) . 74 + 16
= [(-16) + 16] . [74 + (-16)] . 27
= 0 . 58 . 27
= 0 . 27
= 0
b) 38. (78 - 59) - 78 . (38 - 59)
= (38 - 38) . (59 - 59) . (78 - 78)
= 0 . 0 . 0
= 0
