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tính trừ bt nha bạn vế thương thì cũng tĩnh ra xong mới tính nha
a, \(x\) + \(\dfrac{1}{4}\) - \(\dfrac{3}{8}\) = \(\dfrac{7}{12}\)
\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{7}{12}\)
\(x\) = \(\dfrac{7}{12}\) + \(\dfrac{1}{8}\)
\(x\) = \(\dfrac{17}{24}\)
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1) 31-3.(x+2) = 7
3.(x+2) = 31- 7
3.(x+2) = 24
x+2 = 24:3
x + 2 = 8
x = 8-2
x = 6
2) 175-25.(2x-1) = 175
25.(2x-1) = 175- 175 = 0
2x-1 = 0 : 25 = 0
2x = 0 + 1 = 1
x = 1 : 2 = 0,5
3) 25 - x/2 = 19
x/2 = 25-19
x/2 = 6
x : 2 = 6
x = 6 x 2 = 12
4) 2.(x-1)+3 = 15
2.(x-1) = 15 - 3 = 12
x - 1 = 12 : 2 = 6
x = 6+1 = 7
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- Tính giá trị biểu thức:
a) (2/5 x 25/29) + (3/5 x 25/29)
= (50/145) + (75/145)
= 125/145
b) (5/2 x 3/7) - (3/14 : 6/7)
= 15/14 - (3/14 x 7/6)
= 15/14 - 1/2
= (30/28) - (14/28)
= 16/28
= 4/7
c) (15/4 : 5/12) - (6/5 : 11/15)
= (15/4 x 12/5) - (6/5 x 15/11)
= 180/20 - 90/55
= 9 - 18/11
= (99/11) - (18/11)
= 81/11
= 7 4/11
- Tính giá trị biểu thức:
a) (2/3) + (20/21 x 3/2 x 7/5)
= 2/3 + (60/210)
= 2/3 + 2/7
= (14/21) + (6/21)
= 20/21
b) (5/17 x 21/32 x 47/24 x 0)
= 0
c) (11/3 x 26/7) - (26/7 x 8/3)
= (286/21) - (208/21)
= 78/21
= 3 9/21
= 3 3/7
- Tìm x:
a) (25/8) : x = 5/16
=> (25/8) x (16/5) = x
=> 4 = x
b) x + (7/15) = 6/15
=> x = (6/15) - (7/15)
=> x = -1/15
c) x : (28/49) = 7/12
=> x x (49/28) = 7/12
=> x = (7/12) x (28/49)
=> x = 1/2
- Tìm x:
a) 6 x x = (5/8) : (3/4)
=> 6x = (5/8) x (4/3)
=> 6x = 20/24
=> 6x = 5/6
=> x = (5/6) / 6
=> x = 5/36
câu,b,không,đủ,thông,tin,nhan,bạn.
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( x + 1 ) + ( x + 4 ) + ( x + 7 ) + ......... + ( x + 28 ) = 155
<=>(x+x+x...+x)+(1+4+...+28)=155
=>10x+145=155
=>10x=155-145
=>10x=10
=>x=1
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Tìm x
a) 17 + 33 : ( 2 . x - 1 ) = 20
33 :( 2 . x - 1 )= 20 - 17
33 :( 2 . x - 1 ) = 3
2 . x - 1 = 33 : 3
2 . x - 1 = 11
2 . x = 11 - 1 = 10
x = 10 : 2
x = 5
b) 25 - [ ( 2 . x + 5 ) . 7 - 15 ] : 5 = 21
[ ( 2 . x + 5 ) . 7 - 15 ] : 5 = 25 - 21
[ ( 2 . x + 5 ) . 7 - 15 ] : 5 = 4
( 2 . x + 5 ) . 7 - 15 = 5 x 4
( 2 . x + 5 ) . 7 - 15 = 20
( 2 . x + 5 ) . 7 = 20 + 15
( 2 . x + 5 ) . 7 = 35
2 . x + 5 = 35 : 7
2 . x + 5 = 5
2 . x = 5 - 5
2 . x = 0
x = 0
hok tốt
a) \(17+33:\left(2x-1\right)=20\)
\(\Rightarrow33:\left(2x-1\right)=20-17\)
\(\Rightarrow33:\left(2x-1\right)=3\)
\(\Rightarrow2x-1=33:3\)
\(\Rightarrow2x-1=11\)
\(\Rightarrow2x=11+1\)
\(\Rightarrow2x=12\)
\(\Rightarrow x=12:2\)
\(\Rightarrow x=6\)
Vậy x = 6
b) \(25-\left[\left(2x+5\right)\times7-15\right]:5=21\)
\(\Rightarrow\left[\left(2x+5\right)\times7-15\right]:5=25-21\)
\(\Rightarrow\left[\left(2x+5\right)\times7-15\right]:5=4\)
\(\Rightarrow\left(2x+5\right)\times7-15=4\times5\)
\(\Rightarrow\left(2x+5\right)\times7-15=20\)
\(\Rightarrow\left(2x+5\right)\times7=20+15\)
\(\Rightarrow\left(2x+5\right)\times7=35\)
\(\Rightarrow2x+5=35:7\)
\(\Rightarrow2x+5=5\)
\(\Rightarrow2x=5-5\)
\(\Rightarrow2x=0\)
\(\Rightarrow x=0:2\)
\(\Rightarrow x=0\)
Vậy x = 0
_Chúc bạn học tốt_
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a, 53 x 39 + 47 x 39 + 53 x 21- 47 x 21
= ( 53 + 47 ) x 39 + ( 53 - 47 ) x 21
= 100 x 39 + 6 x 21
= 3900 + 126
= 4026
Mấy phần khác bạn tự làm đi
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1) (x-17)*17=0
x-17=0
x=17
2) 32(x-11)=32
x-11=1
x=12
3) (x-25)-75=0
x-25=75
x=3
4) 575-(6*x+70)=445
6*x+70=130
6*x=60
x=10
5) 315+(125-x)=435
125-x=120
x=5
6) x-105:21=15
x-5=15
x=20
7) (x-105):21=15
x-105=315
x=420
8) (x-38):19=12
x-38=228
x=266
9) (x-15)*(x-19)=0
=>x-15=0 hoặc x-19=0
x=15 hoặc x=19
10) 96-3(x+1)=42
3(x+1)=54
x+1=18
x=17
a) ( x - 17 ) . 17 = 0
=> x - 17 = 0 : 17
=> x - 17 = 0
=> x = 0 + 17
=> x = 17
b) 32 . ( x - 11 ) = 32
=> x - 11 = 32 : 32
=> x - 11 = 1
=> x = 1 + 11
=> x = 12
c) ( x - 25 ) - 75 = 0
=> x - 25 = 0 + 75
=> x - 25 = 75
=> x = 75 + 25
=> x = 100
d) 575 - ( 6 . x + 70 ) = 445
=> 6 . x + 70 = 575 - 445
=> 6 . x + 70 = 130
=> 6 . x = 130 - 70
=> 6 . x = 60
=> x = 60 : 6
=> x = 10
e) 315 + ( 125 - x ) = 435
=> 125 - x = 435 - 315
=> 125 - x = 120
=> x = 125 - 120
=> x = 5
f) x - 105 : 21 = 15
=> x - 5 = 15
=> x = 15 + 5
=> x = 20
g) ( x - 105 ) : 21 = 15
=> x -105 = 15 . 21
=> x - 105 = 315
=> x = 315 + 105
=> x = 420
h) ( x - 38 ) : 19 = 12
=> x - 38 = 12 . 19
=> x - 38 = 228
=> x = 228 + 38
=> x = 266
i) ( x - 15 ) . ( x - 19 ) = 0
=> x - 15 = 0 => x = 0 + 15 => x = 15
x - 19 = 0 => x = 0 + 19 = x = 19
=> x = 15 ; 19
j) 96 - 3( x + 1 ) = 42
=> 3( x + 1 ) = 96 - 42
=> 3( x + 1 ) = 54
=> x + 1 = 54 : 3
=> x + 1 = 18
=> x = 18 - 1
=> x = 17