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\(a,\left(2600+6400\right)-3\times x=1200\)
\(9000-3\times x=1200\)
\(3\times x=9000-1200\)
\(3\times x=7800\)
\(x=7800:3\)
\(x=2600\)
\(b,\left[\left(6\times x-72\right):2-84\right]\times28=5628\)
\(\left(6\times x-72\right):2-84=5628:28\)
\(\left(6\times x-72\right):2-84=201\)
\(\left(6\times x-72\right):2=201+84\)
\(\left(6\times x-72\right):2=285\)
\(6\times x-72=285\times2\)
\(6\times x-72=570\)
\(6\times x=570+72\)
\(6\times x=642\)
\(x=107\)
\(c,2x-138=2^3:3^2\)
\(2x-138=\frac{8}{9}\)
\(2x=\frac{8}{9}+138\)
\(2x=\frac{1250}{9}\)
\(x=\frac{1250}{9}:2\)
\(x=\frac{625}{9}\)
\(d,42x=39\times42-37\times42\)
\(42x=42\times\left(39-37\right)\)
\(42x=42\times2\)
\(42x=84\)
\(x=2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
A )123 -5 ( x -4 ) = 38
=> x-4 = (123-38) :(-5)
=> x-4=-17
=> x= -17+4=-13
B ) ( 3x - 24 ) 73 = 2.74
=> 3x-16= 2.74 :73=14
=> 3x=14+16=30
=> x=30:3=10
C ) ( 2600 + 6400 ) - 3x = 1200
=> 9000-3x=1200
=> 3x=9000-1200=7800
=> x=7800:3=2600
D ) [( 6x - 72 ) : 2 - 84 ] 28 = 5628
=> (6x-72) :2-84= 5628:28=201
=> 6x-72 = (201+84) .2=570
=> 6x=570 +72=642
=> x= 642:6=107
( L-IKE )
A) 123 - 5(x-4) = 38
5(x-4) = 123 - 38
x-4 = 85 : 5
x = 17 + 4
x= 21
B) (3x - 24)73 = 2.74
(3x - 24) = 2.74:73
3x = 14 + 24
x = 30 : 3 = 10
C) (2600 + 6400) - 3x = 1200
9000 - 3x = 1200
3x = 9000 - 1200
x = 7800 : 3 = 2600
D) [(6x - 72) : 2 - 84].28 = 5628
(6x - 72) : 2 - 84 = 5628 : 28 = 201
(6x - 72) : 2 = 201 + 84 = 285
6x - 72 = 285 . 2 = 570
6x = 570 + 72 = 642
x = 642 : 6 = 107
Có thể thử lại đáp án
![](https://rs.olm.vn/images/avt/0.png?1311)
#)Giải :
\(123-5\left(x+4\right)=38\)
\(\Leftrightarrow5\left(x+4\right)=85\)
\(\Leftrightarrow x+4=17\)
\(\Leftrightarrow x=13\)
\(\left(3x-16\right)343=2.2401\)
\(\Leftrightarrow\left(3x-16\right)343=4802\)
\(\Leftrightarrow3x-16=14\)
\(\Leftrightarrow3x=30\)
\(\Leftrightarrow x=10\)
\(\left(2600+6400\right)-3x=1200\)
\(\Leftrightarrow9000-3x=1200\)
\(\Leftrightarrow3x=7800\)
\(\Leftrightarrow x=2600\)
P/s : Câu cuối cùng lỗi chỗ b4 ph k ? hay là tìm cả b và x thế ???
\(123-5\left(x+4\right)=38\)
\(=>123-5x-20=38\)
\(=>-5x=-123+20+38\)
\(=>-5x=-65\)
\(=>x=13\)
b, \(\left(3x-16\right)343=2.2401\)
=>1029x -5488= 4802
=> 1029x=5488+4802
=> 1029x= 10290
=> x=10
c, (2600+6400)-3x=1200
=> 9000-3x=1200
=> -3x= -9000+1200
=> -3x= -7800
=> x=2600
d,
k hiểu đề
![](https://rs.olm.vn/images/avt/0.png?1311)
5.(x-4)=123-38
5.(x-4)=85
x-4=85:5
x-4=17
x=17+4
x=21
Đúng 1000000000000000
![](https://rs.olm.vn/images/avt/0.png?1311)
Tất cả tập hợp con của tập hợp A là:
B = {1} ; B = {2} ; B = {3} ; B = {1;2} ; B = {1;3} ; B = {2;3} ; B = {1;2;3}
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 9000 - 3 . x=1200
3.x =9000 - 1200
3.x =7800
x =7800:3
x=2600
b) [(6x - 72) : 2 - 84]. 28 = 5628
[(6x - 72) : 2 - 84] = 5628 : 28
(6x - 72) : 2 - 84 = 201
(6x - 72) : 2 = 201 + 84
(6x - 72) : 2 = 285
(6x - 72) = 285 . 2
6x - 72 = 570
6x =570+72
6x = 642
x = 642 : 6
x = 107
c) (3. x - 2^4) = 2. 7^4 : 7^3
(3. x - 16) = 2. 7
3. x - 16 = 14
3. x = 14 + 16
3. x = 30
x = 30 : 3
x = 10
a) (2600+6400) - 3. x = 1200
9000-3.x=1200
3.x=9000-1200
3.x=7800
x=7800:3
x=2600
b) [(6x - 72) : 2 - 84]. 28= 5628
[(6x - 72) : 2 - 84] =5628:28
(6x - 72) : 2 - 84 =201
(6x - 72) : 2 =201+84
(6x - 72) : 2 = 285
(6x - 72) =285x2
6x - 72 =570
6x =570+72
6x =642
x =642:6
x =107
c) (3. x - 24) . 73= 2. 74
tí nk làm,mà bài này dễ bạn tự suy nghĩ đi,tính lũy thừa trước nà
![](https://rs.olm.vn/images/avt/0.png?1311)
a,(2600+6400)-3 .x = 1200
=> 9000-3 .x= 1200
=> 3.x= 7800
=. x=2600
b, (6.x-72):2-84= 201
(6x-72):2=285
6x-72=570
6x=642
x=107
a) ( 2600 + 6400 ) - 3 . x = 1200
9000 - 3 . x = 1200
3 . x = 9000 - 1200
3 . x = 7800
x = 7800 : 3
x = 2600
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left(2600+6400\right)-3-x=1200\)
\(\Rightarrow9000-3-x=1200\)
\(\Rightarrow3-x=9000-1200\)
\(\Rightarrow3-x=7800\)
\(\Rightarrow x=7797\)
b) \(\left[\left(6\cdot x-72\right):2-84\right]\cdot28=5628\)
\(\Rightarrow\left[\left(6\cdot x-72\right):2-84\right]=5628:28\)
\(\Rightarrow\left[\left(6\cdot x-72\right):2-84\right]=201\)
\(\Rightarrow\left(6\cdot x-72\right):2=201+84\)
\(\Rightarrow\left(6\cdot x-72\right):2=285\)
Đến dei bạn tự làm, ý b mình không chắc chắn lắm
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (2600 + 6400) - 3 . x = 1200
9000 - 3.x = 1200
3x = 9000-1200
3x = 7800
x = 7800:3
x = 2600
b) câu này ko có tổng hả Công chúa nhí nhảnh? check lại giùm Nhi nha!
a) \(\left(2600+6400\right)-3x=1200\)
\(9000-3x=1200\)
\(3x=9000-1200\)
\(3x=7800\)
\(x=\frac{7800}{3}\)
\(x=2600\)
vậy \(x=2600\)
b) \(\left[\left(6x-72\right):2-84\right].28+5628=0\)
\(\left[\frac{6x}{2}-\frac{72}{2}-84\right].28+5628=0\)
\(\left[3x-36-84\right].28=-5628\)
\(3x-120=\frac{-5628}{28}\)
\(3x-120=-201\)
\(3x=-201+120\)
\(3x=-81\)
\(x=-27\)
vậy \(x=-27\)
123-5.(x+4)=38
5.(x+4)=123-38
5.(x+4)=85
x+4=85:5
x+4=17
x=17-4
x=13
(3.x-2^4).7^3=2.7^4
(3.x-16).343=2.2401
(3.x-16).343=4802
3.x-16=4802:343
3.x-16=14
3.x=14+16
3.x=30
x=30:3
x=10
6^2:4.3+2.5^2
=36:4.3+2.25
=9.3+2.25
=27+50
=77
5.4^2-18:3^2
=5.16-18:9
=80-2
=78
80-(4.5^2-3.2^3)
=80-(4.25-3.8)
=80-(100-24)
=80-76
=4
23.75+25.23+180
=23.(75+25)+180
=23.100+180
=2300+180
=2480
2448:[119-(23-6)]
=2448:(119-17)
=2448:102
=24
(2600+6400)-3.x=1200
9000-3.x=1200
3.x=9000-1200
3.x=7800
x=7800:3
x=2600
[(6.x-72):2-84].28=562
(6.x-72):2-84=562:28
(6.x-72):2-84=281/14
(6.x-72):2=281/14+84
(6.x-72):2=1457/14
6.x-72=1457/14.2
6.x-72=1457/7
6.x=1457/7+72
6.x=1961/7
x=1961/7:6
x=1961/42