Bài1
a)12.(-23)+(-23).88 = -2300
b)-20<x<21
⇒ x ∈ {-19, -18, -17, -16, -15, -16, ...., 16,17, 18, 19, 20 }
Bài 2:
a) 25.(-125).(-8).(-4)
= - ( 25 . 125 . 8 . 4 )
= -( 25 . 4) . ( 125 . 8 )
= -100 . 1000 = -100 000
b, 15.(-23)+15.23
= 15 . ( -23 + 23 )
= 15 . 0 = 0
c) 176.(-26)-26.824
= 176 . (-26 ) + ( -26 ) . 824
= -26 . ( 176 + 824)
= -26 . 1000 = -26 000
d) (-123).86+123.(-14)
= 123 . ( -86 ) + 123 . ( -14 )
= 123 . [- ( 86 + 14 ) ]
= 123 . (-100) = -12 300