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a) \(56+\left(-29\right)+\left(-7\right)+28+13+\left(-35\right)\)
\(=27+\left(-7\right)+28+13+\left(-35\right)\)
\(=20+28+13+\left(-35\right)\)
\(=48+13+\left(-35\right)\)
\(=61+\left(-35\right)\)
\(=26\)
b) \(\left(-213\right)+186+\left(-14\right)+217+54+\left(-49\right)\)
\(=\left(-27\right)+\left(-14\right)+217+54+\left(-49\right)\)
\(=\left(-41\right)+217+54+\left(-49\right)\)
\(=176+54+\left(-49\right)\)
\(=230+\left(-49\right)\)
\(=181\)
c) \(435+\left(-43\right)+\left(-483\right)+\left(-57\right)+383+\left(-415\right)\)
\(=392+\left(-483\right)+\left(-57\right)+383+\left(-415\right)\)
\(=\left(-91\right)+\left(-57\right)+383+\left(-415\right)\)
\(=\left(-148\right)+383+\left(-415\right)\)
\(=235+\left(-415\right)\)
\(=-180\)
7)\(\dfrac{-19}{34}\left(\dfrac{17}{19}+\dfrac{49}{18}\right)+\dfrac{49}{18}\left(\dfrac{19}{34}-\dfrac{18}{7}\right)\)
=\(\dfrac{-19}{34}.\dfrac{17}{19}+\dfrac{49}{18}.\dfrac{-19}{34}+\dfrac{49}{18}.\dfrac{19}{34}-\dfrac{18}{7}.\dfrac{49}{18}\)
=\(\dfrac{1}{2}+\left(\dfrac{49}{18}.\dfrac{-19}{34}+\dfrac{49}{18}.\dfrac{19}{34}\right)-7\)
=\(\dfrac{1}{2}+\left[\dfrac{49}{18}\left(\dfrac{-19}{34}+\dfrac{19}{34}\right)\right]-7\)
=\(\dfrac{1}{2}+0-7=\dfrac{-13}{2}\)
8)\(\dfrac{29}{32}\left(\dfrac{41}{36}-\dfrac{32}{58}\right)-\dfrac{41}{36}\left(\dfrac{29}{32}+\dfrac{18}{41}\right)\)
=\(\dfrac{29}{32}.\dfrac{41}{36}-\dfrac{29}{32}.\dfrac{32}{58}-\dfrac{41}{36}.\dfrac{29}{32}+\dfrac{18}{41}.\dfrac{41}{36}\)
=\(\left(\dfrac{29}{32}.\dfrac{41}{36}-\dfrac{41}{36}\dfrac{29}{32}\right)-\dfrac{29}{32}.\dfrac{32}{58}+\dfrac{18}{41}.\dfrac{41}{36}\)
=\(0-\dfrac{1}{2}+\dfrac{1}{2}=0\)
a)
Cách 1:
15.12 – 3.5.10 = 180 - 150 = 30
Cách 2:
15.12 – 3.5.10 = 15.12 – 15.10 = 15.(12 - 10) = 15.2 = 30
b)
Cách 1:
45 – 9.(13 + 5) = 45 – 9.18 = 45 - 162 = -117
Cách 2:
45 – 9.(13 + 5) = 9.5 – 9.13 – 9.5 = 9.5 – 9.5 – 9.13
= -9.13 = -117
c)
Cách 1:
29.(19 - 13) – 19.(29 - 13) = 29.6 – 19.16 = 174 – 304 = -130
Cách 2:
29.(19 - 13) – 19.(29 - 13) = 29.19 - 29.13 - 19.29 + 19.13
= 29.19 - 29.19 - 29.13 + 19.13 = 13.(-29 + 19)
= 13.(-10) = -130
Cách 1:
a) 15.12-3.5.10
=180-150
=30
b) 45−9.(13+5)
=45-9.18
=45-162
=-117
c) 29.(19−13)−19.(29−13)
=29.6-19.16
=174-304
=-130
Cách 2.
a) 15.12−3.5.10
=15.12-15.10
=15.(12-10)
=30
b) 45−9.(13+5)
=45-9.13-45
=-117
c) 29.(19−13)−19.(29−13)
=29.19-29.13 - 19.29 - 19. -13
=-29.13 - 19. -13
=-13.(29-19)
=-130
( - 12 ) . ( - 13 ) + 13 . ( - 29 )
= \(12.13+13.\left(-29\right)\)
=\(13.\left[12+\left(-29\right)\right]\)
=\(13.\left(-17\right)\)
=\(-221\)
a) (-12).(-13) + 13.(-29)
= 12.13 + 13.(-29)
= 13.(12 - 29)
= 13 . (-17)
=-221
b) -23.63 + 23.21 - 58.23
= -(23.63 - 23.21 + 58.23)
= -23.(63 - 21 + 58)
= -23.100
=-2300
a) (27+65)+(346-27-65)
= 27+65+346-27-65
= (27-27)+(65-65)+346
= 0 + 0 + 346
= 346
b) (42-69+17)-(42+17)
= 42-69+17 – 42 – 17
= (42-42)+(17-17)-69
= 0 + 0 – 69
= -69
a)(27+65)+(346-27-65)
=27+65+345-27-65
=(27-27)+(65-65)+346
=0+0+346
=346
b) (42-69+17)-(42+17)
=42-69+17-42-17
=(42-42)-69+(17-17)
=0-69+0
=-69
-
Tích hai số cùng dấu thì dương.
-
Tích hai số khác dấu thì âm.
Với các phép tính nhân hai số nguyên khác dấu, nếu bạn đã thực sự làm quen rồi thì có thể bỏ bước nhân giá trị tuyệt đối đi cũng được.
a) (-25) .8 = -(|-25|.|8|) = -(25.8) = -200
b) 18.(-15) = -(|18|.|-15|) = -(18.15)= -270
c) (-1500).(-100) = |-1500|.|-100| = 1500.100 = 150000
d) (-13)2 = (-13).(-13) = |-13|.|-13| = 13.13 = 169
a) (-25) .8 = -(|-25|.|8|) = -(25.8) = -200
b) 18.(-15) = -(|18|.|-15|) = -(18.15)= -270
c) (-1500).(-100) = |-1500|.|-100| = 1500.100 = 150000
d) (-13)2 = (-13).(-13) = |-13|.|-13| = 13.13 = 169
Tính :
a) (26−6).(−4)+31(−7−13)
=20.(-4)+31.(-20)
=-20(4+31)
=(-20).35
=-700
b) (−18).(55−24)−28.(44−68)
=(-18). 31- 28. (-24)
=6.(-3).31-28.(-4).6
=6. (-93)+ 112.6
=6.(-93+112)=114
a) 18 + 29 - 158 - 29 - 18 = -158
b) 13 - 135 + 49 - 13 - 49 = -136
tick nha
a) =18+29+158-29-18=18-18+29-29+158=0+0+158=158
b) =13-135+49-13-49=13-13+49-49-135=0+0-135=-135
Tick nha
a, (18+29) +(158-18-29)
= 18+29+158-18-29
= (18-18) +(29-29)+ 158
= 158
b, (13-135+49)- (13+49)
= 13-135+49-13-49
= (13-13) +(49-49) -135
= 135
a, \(\left(18+29\right)+\left(158-18-29\right)\)
\(=18+29+158-18-29\)
\(=\left(18-18\right)+\left(29-29\right)+158\)
\(=158\)
b,
\(\left(13-135+49\right)-\left(13+49\right)\)
\(=13-135+49-13-49\)
= \(\left(13-13\right)+\left(49-49\right)-135\)
= \(-135\)