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a) -87 + (-12) - (-487) + 512
= [-87 - (-487)] + [(-12) + 512]
= 400 + 500
=900
b) 942 - 2567 + 2563 -1942
= (942 - 1942) + (-2567 + 2563)
= -1000 + (-4)
=-1004
c)[ 53 + (-76) ] - [ -76 - (-53) ]
= 53 + (-76) + 76 -53
= (53 - 53) + [(-76) + 76]
=0 + 0
=0
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{3}{2}.\frac{7}{2}+\frac{5}{3}.\frac{1}{2}=\frac{21}{2}+\frac{5}{6}=\frac{63}{6}+\frac{5}{6}=\frac{68}{6}=\frac{34}{3}\)
b) \(\frac{1}{9}.\frac{2}{145}-\frac{13}{3}.\frac{2}{145}+\frac{2}{145}=\frac{2}{145}\left(\frac{1}{9}-\frac{39}{9}+\frac{9}{9}\right)=\frac{2}{145}\left(-29\right)=-0.4\)
c) \(\left(-\frac{91}{12}\right):\frac{15}{7}-\frac{1}{18}:\frac{15}{7}+\frac{20}{9}:\frac{15}{7}=\frac{7}{15}\left(-\frac{91}{12}-\frac{1}{18}+\frac{20}{9}\right)=\frac{7}{15}\left(-\frac{65}{12}\right)=-\frac{91}{36}\)
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a)160 - ( 12 . 10 - 6 . 25 )
=160 - (120 - 150 )
=160 - (-30)
=190 = 2.5.19
B) 500 - { 5. [409 - (12.3-42)]+60} : 15
=500 - { 5. [ 409 - (-6)] + 60 } :15
=500 - { 5. 415 + 60 } :15
=500 -{ 2075 + 60} : 15
=500 - {2075 + 60 } :15
=500 - 2135 : 15
=500 - \(\dfrac{427}{3}\)
=\(\dfrac{1073}{3}\)
c)(-16) + (-48) + 164
= -64 + 164
= 100 = 22 x 52
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số số hạng của S là :(2015-13):2+1=1002 (số số hạng)
tổng của S là :(2015 +13) .1002 :2 =1015026
2)160 - (4. 5^2 -3 .2^3)
=160-(4.25-3 . 8)
=160-(100-24)
=160-76
=84
3)
a)2015-[117-(23-6)]
=2015-[117-17]
=2015-100
=1915
![](https://rs.olm.vn/images/avt/0.png?1311)
c) (-37) – 14 – 26 + 37=(-37)+37-14-26=0-(-12)=12
d) 34 + 35 + 36 + 37 – 14 – 15 – 16 – 17 =(34-14)+(35-15)+(36-16)+(37-17)=20+20+20+20=80
g,-87+(-12)-(-487)+512=(-87+512)+[(-12)-(-487)]=425+475=900
![](https://rs.olm.vn/images/avt/0.png?1311)
a)17.85-15.17-120
=17.(85-17)-120
=17.68-12
=1156-120
=1036
b)100:[30-(6-1)^ 2]
=100 :[30-5^ 2]
= 100:[30-25]
=100:5=20
c)/-10/+4+3.2^3+(-14)
=10+4+3.8 +(-14)
=14+24+(-14)
=[14 +(-14)]+24
=0+24=24
d)20-[30-(5-1)^ 2: 2]
=20-[30-4^2:2]
=20-[30-8]
=20-22=-2
e)80-(4.5^2-3.2^3)
= 80-(4.25-3.8)
=80-(4.25-3.2.4)
=80-4.(25-3.2)
= 80-4.19
= 80-76=4
g)35-{12-[-14+6-2)]}
=35 -{12-14-6+2}
=35-12+14+6-2
=23+14+6-2
=37+6-2
=43-2=41
\(-87+12-\left(-487\right)+\left(-512\right)\\ =\left(-87+487\right)+\left[12+\left(-512\right)\right]\\ =400+\left(-500\right)\\ =-100\\ 15.\left(-12\right)+15.\left(-18\right)\\ =15.\left[\left(-12\right)+\left(-18\right)\right]\\ =15.\left(-30\right)\\ =-450\\ 160-\left(4.5^2-3.2^3\right)\\ =160-\left(4.25-3.8\right)\\ =160-\left(100-24\right)\\ =160-76\\ =84\)