a,b a×(−2)×b×3 ÷ 4 0 a,b
−1
−5
+5
−8 −4 +4 +8
38−(−24)−18
= 38−[(−24)−18]
= 38−(−42)
= 38 + 42
= 80
(−5)×3
(−5) + 3 (−5) + (−3) (−5) + (−5) + (−5) (−3) + (−3)
|−9|+|−8| = 1 |−9|−|8|= 1
|−6|+|−8| = −14 |−6|−|8| = 2 A(3),B(4),C(−5),D(−6)
AB AC BD BC
916×12×31 = 916×(12×31) 432 ÷ 4 ÷ 2 = 432 ÷ (4 ÷ 2) 972 ÷ 8×4 = 972 ÷ (8 ÷ 4)
493×16 ÷ 4 = 493×(16 ÷ 4)
A,B,C,P P
a > 0 b < 0 a >b b >c
50−15−20 50 + (15−20) 50−(15 + 20) 50 + (−15) + (−20) a = −1.4 b = − 4
3 c = |−1.4| d = |− 4 3|
a < b <d < c a <b < c < d b < a < c < d b < a < d< c
a,b a b
|a|+b > 0 a+|b| > 0 −a+b = 0 a+b = 0 A,B
A+B A−B A× B A÷B
a = (−12)−(−6) ÷ 6 b = [(−12)−(−6)] ÷ 6 a,b a <b a = b a > b
−3 10
8 13 −8 −13
> , = <
−8.3 −8.38 −0.5 −1 2
|4 1
2| |−5 1
3| −|−8| |−10|
A,B,C,D,E,F
A B C D E F
(−29) + 27 = 8−(−61) =
12×(−31) + 12×(−69) = 24 ÷ (−3) ÷ (−4) =
|a−d| = 20,
|b−a| = 7,|d−c|= 6 BC = (−2) + (−3)×|8 + (−10) ÷ 5| =
O
a,b |a| = a+ 3 |a + 3|×b = a−3 |a−b|−|a+b| =
− 1 2 4 − 4
2 3 4
7
=
2
>
6 4 5
<
69
−2
− 20 7
10
−6
>
− 1200
−4 1 3
−203−7×8 =−259
259 0 + 1×2−4×3 + 3×2 =−4
−4
−203 + 8×16 =−75
75
−3
