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a) 85 - ( 3 . 52 - 4 . 32 )
= 85 - ( 3 . 25 - 4 . 9 )
= 85 - ( 75 - 36 )
= 85 - 39
= 46
b) 9 . 23 - ( 711 : 72 + 12015 + 20160 )
= 72 - ( 79 + 12015 + 0 )
= 72 - 40353608
= - 40353536
c) 24 : { 390 : [ 500 - ( 53 + 49 . 5 )]}
= 24 : [ 390 : ( 500 - 370 ) ]
= 24 : ( 390 : 130 )
= 24 : 3
= 8
d) 2 + 4 + 6 + ... + 1000
Có số số hạng là:
( 1000 - 2 ) : 2 + 1 = 500 ( số )
Tổng là:
( 1000 + 2 ) . 500 : 2 = 250500
![](https://rs.olm.vn/images/avt/0.png?1311)
24 : { 390 : [ 500 - ( 125 + 35 . 7 )]} - 32
= 24 : { 390 : [ 500 - ( 125 + 245 )]} - 9
= 24 : { 390 : [ 500 - 370 ]} - 9
= 24 : { 390 : 130} - 9
= 24 : 3 - 9
= 8 - 9 = -1
k mik nha, thank nhiều nhiều
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![](https://rs.olm.vn/images/avt/0.png?1311)
\(24:\left\{390-[500-\left(125+35.7\right)]\right\}=2^x\)
\(24:\left\{390-[500-\left(125+245\right)]\right\}=2^x\)
\(24:\left\{390-[500-370]\right\}=2^x\)
\(24:\left\{390-130\right\}=2^x\)
\(24:260=2^x\)
Chỗ này sai đề ạ !
24 : { 390 - [ 500 - ( 125 + 35 . 7 ) ] } = 2x
2x = 24 : { 390 - [ 500 - ( 125 + 245 ) ] }
2x = 24 : { 390 - [ 500 - 370 ] }
2x = 24 : { 390 - 130 }
2x = 24 : 260
2x = 6/65 = ......................
=> Đề sai
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![](https://rs.olm.vn/images/avt/0.png?1311)
12:{390:[500-(5^3+5.7^2) ] }
=12:{390:[500-(125+245 ) ] }
=12:{390:[500-370] }
=12:{390:130}
=12:3
=4
\(12:\left\{390:\left[500-\left(5^3+5.7^2\right)\right]\right\}\)
\(=12:\left\{390:\left[500-\left(125+5.49\right)\right]\right\}\)
\(=12:\left\{390:\left[500-\left(125+245\right)\right]\right\}\)
\(=12:\left\{390:\left[500-370\right]\right\}\)
\(=12:\left\{390:130\right\}\)
\(=12:3\)
\(=4\)
_Chúc bạn học tốt_
![](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)
`@` `\text {Ans}`
`\downarrow`
`a,`
`x - 280 \div 35 = 554`
`=> x - 8 = 554`
`=> x = 554 + 8`
`=> x = 562`
Vậy, `x = 562`
`b,`
`x + (5 \div 3) = 500`
`=> x + 5/3 = 500`
`=> x = 500 - 5/3`
`=> x = 1495/3`
Vậy, `x = 1495/3`
`c,`
`390 \div (5x - 5) = 39`
`=> 5x - 5 = 390 \div 39`
`=> 5x - 5 = 10`
`=> 5x = 10 + 5`
`=> 5x = 15`
`=> x = 15 \div 5`
`=> x = 3`
Vậy, `x = 3`
`d,`
`34x - 14x = 200`
`=> (34 - 14)x = 200`
`=> 20x = 200`
`=> x = 200 \div 20`
`=> x = 10`
Vậy, `x = 10.`
`@` `\text {Kaizuu lv uuu}`
a) \(x-280:35=554\)
\(x-8=554\)
\(x=562\)
b) \(x+\left(5:3\right)=500\)
\(x+\dfrac{5}{3}=500\)
\(x=500-\dfrac{5}{3}=\dfrac{1500}{3}-\dfrac{5}{3}=\dfrac{1495}{3}\)
c) \(390:\left(5x-5\right)=39\)
\(5x-5=\dfrac{39}{390}=\dfrac{1}{10}\)
\(5x=5+\dfrac{1}{10}\)
\(5x=\dfrac{51}{10}\)
\(x=\dfrac{51}{10}.\dfrac{1}{5}=\dfrac{51}{50}\)
d) \(34x-14x=200\)
\(20x=200\)
\(x=200:20=10\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =250:{5*(78-28)}
=250:{5*50}
=1
b: \(=3\cdot\left\{150:\left[152-77\right]\right\}\)
=3*{150:75}
=3*2=6
c: \(=12:\left\{390:\left[500-125-245\right]\right\}\)
=12:3=4
d: =100-[16*5+88]:28
=100-6=94
\(24:\text{ }\left\{390:\text{ }\left[500-\left(5^3+49.5\right)\right]\right\}\)
\(=24:\left\{390:\left[500-\left(125+245\right)\right]\right\}\)
\(=24:\text{ }\left\{390:\left[500-370\right]\right\}\)
\(=24:\left\{390:130\right\}\)
\(=24:3\)
\(=8\)