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![](https://rs.olm.vn/images/avt/0.png?1311)
a) -72.17+72.31 - 36 . 228
= -72.17 + 72. 31 - 36.2.114
= -72 .17 + 72 . 31 -72 . 114
= -72. ( 17-31+114)
= -72 . 100
= -7200
b) ..........
= -7 . ( 16-36.9) -(-125)
= -7 . ( 16-324) +125
=-7 . ( -308) +125
= 2156+125
= 2281
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 71.2 – 6.(2x+5) = 10 5 : 10 3
71.2 – 6.(2x+5) = 10 2
6.(2x+5) = 71.2 – 100
6.(2x+5) = 42
x = 1
b, 5 x + 3 4 . 6 8 = 6 9 . 3 4
5 x + 3 4 . 6 8 = 6 8 . 6 . 3 4
5 x + 3 4 = 6 8 . 6 . 3 4 : 6 8 = 6 . 3 4
5x = 6 . 3 4 - 3 4 = 5 . 3 4
x = 3 4
c, 12:{390:[5. 10 2 – ( 5 3 + x . 7 2 )]} = 4
390:[5. 10 2 – ( 5 3 + x . 7 2 )] = 12:4 = 3
5. 10 2 – ( 5 3 + x . 7 2 ) = 390:3 = 130
5 3 + x . 7 2 = 5. 10 2 – 130 = 370
x . 7 2 = 370 – 5 3 = 245
x = 245: 7 2 = 5
d, 5 3 .(3x+2):13 = 10 3 : 13 5 : 13 4
5 3 .(3x+2):13 = 10 3 : 13
3x+2 = 10 3 : 13 : 5 3 .13 = 8
x = 2
![](https://rs.olm.vn/images/avt/0.png?1311)
=> (42-x). 5= 125
=> (42-x)=125: 5
=> (42-x)=25
=> x=42-25
=>x= 17
21.43 -27.21
=21. (43-27)
=21.16
=336
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(12:\left\{390:\left[500-\left(5^3+7^2.5\right)\right]\right\}\)
\(=12:\left\{390:\left[500-125-245\right]\right\}\)
\(=12:\left(390:130\right)\)
\(=12:3=4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
60 : 5 : [390 : ( 13.12 + 13.15 - 7.13 )]
= 60 : 5 : {390 : [ 13 .( 12 + 15 - 7 )]}
= 60 : 5 : {390 : [ 13.20 ]}
= 60 : 5 : {390 : 260}
= 60 : 5 : 1,5
= 12 : 1,5
= 8
![](https://rs.olm.vn/images/avt/0.png?1311)
5^2.53-50.17+25.3^4
=25.53-25.2.17+25.81
=25(53+81-34)
=25(134-34)
=25.100=2500
![](https://rs.olm.vn/images/avt/0.png?1311)
d)102−96+90−84+78−72+66−60+54−48
=(102−72)−(96−66)+(90−60)−(84−54)+(78−48)
=30−30+30−30+30
=30
nha bạn chúc bạn học tốt ạ
![](https://rs.olm.vn/images/avt/0.png?1311)
`a, = 53 xx (12+172 -84)`
`= 53 xx 100`
`=5300`
`b,= 2018 xx (91-45-46)`
`= 2018 xx 0`
`=0`
=45:(390:(5*100-(125+49*5)
=45:(390:(500-(125+245)
=45:(390:(500-370)
=45:(390:130)
=45:3
=15
tick nhé
45 : ( 390 : ( 5 x 102 - ( 53 + 72 x 5 )))
=45 : ( 390 : ( 5 x 100 - ( 125+ 49 x 5 )))
=45 : ( 390 : ( 5 x 100 - (125+245)))
=45 : ( 390 : ( 5 x 100 - 370))
=45 : ( 390 : (500-370))
=45:(390:130)
=45:3
=15