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Câu 5:
a: \(31\cdot\left(-18\right)+31\cdot\left(-81\right)-31\)
\(=31\left(-18-81-1\right)\)
\(=31\cdot\left(-100\right)=-3100\)
b: \(\left(-12\right)\cdot47+\left(-12\right)\cdot52+\left(-12\right)\)
\(=\left(-12\right)\left(47+52+1\right)\)
\(=-12\cdot100=-1200\)
c: \(13\cdot\left(23+22\right)-3\cdot\left(17+28\right)\)
\(=13\cdot45-3\cdot45\)
\(=45\cdot10=450\)
d: \(-48+48\left(-78\right)+48\left(-21\right)\)
\(=48\left(-1-78-21\right)\)
\(=48\left(-100\right)=-4800\)
Câu 4:
a: \(\left(-6-2\right)\left(-6+2\right)=\left(-8\right)\cdot\left(-4\right)=32\)
b: \(\dfrac{\left(7\cdot3-3\right)}{-6}=\dfrac{21-3}{-6}=\dfrac{18}{-6}=-3\)
c: \(\left(-5+9\right)\cdot\left(-4\right)=4\cdot\left(-4\right)=-16\)
d: \(\dfrac{72}{-6\cdot2+4}=\dfrac{72}{-12+4}=\dfrac{72}{-8}=-9\)
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a) 2.(-25).(-4).50 = 10000
b) 16.50.(-25).(-250) = 5000000
c)
− 167 . − 83 + 167.17 − 33 = 167.83 + 167.17 − 33 = 167. 83 + 17 − 33 = 167.100 − 33 = 1667
d)
135 − 35 .47 − 53. − 48 − 52 = 100.47 − 53. − 100 = 100.47 + 53.100 = 100. 47 + 53 = 100.100 = 10000
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a) 2. − 25 . − 4 .50 = 10000
b) 16.50. − 25 . − 250 = 5000000
c)
− 167 . − 83 + 167.17 − 33 = 167.83 + 167.17 − 33 = 167. 83 + 17 − 33 = 167.100 − 33 = 1667
d)
135 − 35 .47 − 53. − 48 − 52 = 100.47 − 53. − 100 = 100.47 + 53.100 = 100. 47 + 53 = 100.100 = 10000
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =6^2-15*2
=36-30=6
b: =3*25+15*4-3
=72+60
=132
c: =25*2+5
=50+5
=55
d: =5+12=17
e: =7^2(15-5)=49*10=490
f: =4^3*125-125:25
=1000-5
=995
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`@` `\text {Ans}`
`\downarrow`
`1,`
`a)`
`-7/25 + (-8)/25`
`= (-7 - 8)/25`
`= -15/25`
`= -3/5`
`b)`
`6/13 + (-15)/39`
`= 18/39 + (-15)/39`
`= (18 - 15)/39`
`= 3/39`
`= 1/13`
`c)`
`5/7 + 4/(-14)`
`= 10/14 + (-4)/14`
`= (10 - 4)/14`
`= 6/14`
`= 3/7`
`d)`
`-8/18 + (-15)/27`
`= -4/9 + (-5)/9`
`= (-4-5)/9`
`= -9/9 = -1`
`2,`
`a)`
`3/5 + (-7)/4`
`= 12/20 + (-35)/20`
`= (12 - 35)/20`
`=-23/20`
`b)`
`(-2) + (-5)/8`
`= (-16)/8 + (-5)/8`
`= (-16 - 5)/8`
`= -21/8`
`c)`
`1/8 + (-5)/9`
`= 9/72 + (-40)/72`
`= (9-40)/72`
`= -31/72`
`d)`
`6/13 + (-14)/39`
`= 18/39 + (-14)/39`
`= (18 - 14)/39`
`= 4/39`
`e)`
`(-18)/24 + 15/21`
`= (-3)/4 + 5/7`
`= (-21)/28 + 20/28`
`= (-21 + 20)/28`
`= -1/28`
a) 25 = 2.2.2.2.2 = 32
b) 33 = 3.3.3 = 27
c) 52 = 5.5 =25
d) 109 =10.10.10.10.10.10.10.10.10 = 1 000 000 000