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a.
\(1,25\times4-x=2,5\)
\(5-x=2,5\)
\(x=5-2,5\)
\(x=2,5\)
b.
\(\left(158-x\right)\div7=20\)
\(158-x=20\times7\)
\(158-x=140\)
\(x=158-140\)
\(x=18\)
c.
\(x-0,25=\frac{43}{4}-\frac{18}{5}\)
\(x-\frac{1}{4}=\frac{43}{4}-\frac{18}{5}\)
\(x=\frac{43}{4}-\frac{18}{5}+\frac{1}{4}\)
\(x=\left(\frac{43}{4}+\frac{1}{4}\right)-\frac{18}{5}\)
\(x=\frac{44}{4}-\frac{18}{5}\)
\(x=11-\frac{18}{5}\)
\(x=\frac{37}{5}\)
a. 1,25 × 4 - x = 2,5
5- x= 2,5
x= 5-2,5
x=2,5
b.(158- x) :7= 20
158- x= 20x7
158 -x= 140
x=158- 140
x=18
c. x- 0,25= \(\frac{43}{4}+\frac{18}{5}\)
x- 0,25=14,35
x= 14,35+ 0,25
x=14,6
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1. \(x-8+32=68\)
\(x-8=68-32\)
\(x-8=36\)
\(x=36+8\)
\(x=44\)
_____
2. \(x+8+32=68\)
\(x+8=68-32\)
\(x+8=36\)
\(x=36-8\)
\(x=28\)
_____
3. \(98-x+34=43\)
\(98-x=43-34\)
\(98-x=9\)
\(x=98-9\)
\(x=89\)
_____
4. \(98+x-34=43\)
\(98+x=43+34\)
\(98+x=77\)
\(x=77-98\)
\(x=-21\)
_____
5. \(x:5:4=800\)
\(x:5=800.4\)
\(x:5=3200\)
\(x=3200.5\)
\(x=16000\)
_____
6. \(18+x=384:8\)
\(18+x=48\)
\(x=48-18\)
\(x=30\)
_____
7. \(\left(84,6-2\times x\right):3,02=5,1\)
\(84,6-2.x=5,1.3,02\)
\(84,6-2.x=15,402\)
\(2.x=84,6-15,402\)
\(2.x=69,198\)
\(x=69,198:2\)
\(x=34,599\)
_____
8. \(x\times5=120:6\)
\(x.5=20\)
\(x=20:5\)
\(x=4\)
_____
9. \(\left(15\times24-x\right):0,25=100:0,25\)
\(\left(15.24-x\right):0,25=400\)
\(15.24-x=400.0,25\)
\(15.24-x=100\)
\(360-x=100\)
\(x=360-100\)
\(x=260\)
1,x-8+32=68
=>x-8=68-32=36
=>x=36+8=42
2,x+8+32=68
=>x+8=68-32=36
=>x=36-8=28
3,98-x+34=43
=>98-x=43-34=9
=>x=98-9=89
4,98+x-34=43
=>98+x=43+34=77
=>x=77-98=-21
5,x:5:4=800
=>x:20=800
=>x=800x20=16000
6,18+x=384:8=48
=>x=48-18=30
7,(84,6-2x):3,02=5,1
=>84,6-2x=5,1x3,02=15,402
=>2x=84,6-15,402=69,198
=>x=69,198:2=34,599
8,5x=120:6=20
=>x=20:5=4
9,(15x24-x):0,25=100:0,25=400
=>360-x=400x0,25=100
=>x=360-100=260.
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a) \(\left(\frac{2x}{5}-1\right):\left(-5\right)=\frac{1}{7}\)
\(\frac{2x}{5}-1=\frac{1}{7}.\left(-5\right)\)
\(\frac{2x}{5}-1=\frac{-5}{7}\)
\(\frac{2x}{5}=\frac{-5}{7}+\frac{7}{7}\)
\(\frac{2x}{5}=\frac{2}{7}\)
\(=>2x.7=2.5\)
\(=>14x=10\)
\(=>x=\frac{5}{7}\)
c) \(\left|3,5+2,5x\right|-2,5=3,5\)
\(\left|3,5+2,5x\right|=3,5+2,5\)
\(\left|3,5+2,5x\right|=6\)
\(TH1\) \(3,5+2,5x=6\) \(TH2\) \(3,5+2,5x=-6\)
\(2,5x=6-3,5\) \(2,5x=-6-3,5\)
\(2,5x=2,5\) \(2,5x=-9.5\)
\(x=1\) \(x=-3,8\)
vậy \(x=1\) hoặc \(x=-3,8\)
câu d) làm tương tự như câu c)
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\(a,\) \(5.\left(4+6x\right)=290\)
\(4+6x=290:5\)
\(4+6x=58\)
\(6x=58-4\)
\(6x=54\)
\(x=54:6\)
\(x=9\left(tm\right)\)
Vậy ..................
\(b,x.3,7+x.6,3=120\)
\(x\left(3,7+6,3\right)=120\)
\(10x=120\)
\(x=120:10\)
\(x=12\left(tm\right)\)
Vậy ....................
c) \(\left(15.24-x\right):0,25=100:\dfrac{1}{4}\)
\(\left(360-x\right):\dfrac{1}{4}=400\)
\(360-x=400.\dfrac{1}{4}\)
\(360-x=100\)
\(x=360-100\)
\(x=260\left(tm\right)\)
Vậy ...................
a) 5. ( 4+6 . x ) = 290
( 4+6 . x ) = 290 : 5
4 + 6 . x = 58
6 .x = 58 - 4
6.x = 54
x = 54 : 6
x = 9
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a, 2,5 x 16,27 x 4 + 7,3
\(=\left(2,5\times4\right)\times16,27+7,3\)
\(=10\times16,27+7,3\)
\(=162,7+7,3\)
\(=170\)
b, 0,25 x 1,25 x 8 x 4 x 0,5
\(=\left(0,25\times4\right)\times\left(1,25\times8\right)\times0,5\)
\(=1\times10\times0,5\)
\(=5\)
c, 500 x 3,26 x 0,02 : 0,5
\(=\left(500\times0,02\right)\times3,26\div0,5\)
\(=10\times3,26\times\frac{10}{5}\)
\(=3,26\times20\)
\(=65,2\)
d, 32,4 x 6,24 + 3,66 x 32,4 + 0,5
\(=32.4\times\left(3,66+6,24\right)+0,5\)
\(=32,4\times9,9+0,5\)
\(=320,76+0,5\)
\(=321,26\)
e, 17,2 x 9,55 + 9,45 x 17,2 + 17,2
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cố gắng tìm nhân tử chung hay nhóm làm sao ra dcd số tròn chục hay trăm j đó là xong rồi
a) 2,5 x 16,27 x 4 + 7,3
= 2,5 x 4 x 16,27 + 7,3
= 10 x 16,27 + 7,3
= 162,7 + 7,3
= 170
b) 0,25 x 1,25 x 8 x 4 x 0,5
= (0,25 x 4) x (1,25 x 8) x 0,5
= 1 x 10 x 0,5
= 10 x 0,5
= 5
c) 500 x 3,26 x 0,02 : 0,5
= 500 x 3,26 x 0,02 x 2
= (500 x 2 x 0,02) x 3,26
= 20 x 3,26
= 2 x 3,26 x 10
= 6,52 x 10
= 65,2
d) 32,4 x 6,24 + 3,66 x 32,4 + 0,5
= 32,4 x (6,24 + 3,66) + 0,5
= 32,4 x 9,9 + 0,5
= 320,76 + 0,5
= 321,26
d) 17,2 x 9,55 + 9,45 x 17,2 + 17,2
= 17,2 x (9,55 + 9,45 + 1)
= 17,2 x 20
= 17,2 x 10 x 2
= 172 x 2
= 344
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x - 0,25 = 43/4 + 18/5
\(x-\frac{1}{4}=\frac{287}{20}\)
\(x=\frac{287}{20}+\frac{1}{4}\)
\(x=\frac{73}{5}\)
\(x-0,25=\frac{43}{4}+\frac{18}{5}\)
\(\Rightarrow x-\frac{1}{4}=\frac{43}{4}+\frac{18}{5}\)
\(\Rightarrow x-\frac{1}{4}=\frac{287}{20}\)
\(\Rightarrow x=\frac{287}{20}+\frac{1}{4}\)
\(\Rightarrow x=\frac{73}{5}\)
\(\Rightarrow x=14,6\)
![](https://rs.olm.vn/images/avt/0.png?1311)
x+0,25 =\(\frac{18}{5}+\frac{43}{4}\)
\(x+\frac{1}{4}-\frac{18}{5}-\frac{43}{4}=0\)
\(\frac{20x+5-72-215}{20}=0\)
20x-282 =0
x= \(\frac{282}{20}\)
x= \(\frac{141}{10}\)
Vậy x=141/10
![](https://rs.olm.vn/images/avt/0.png?1311)
Câu 6: Khôg có cau nào đúng
Câu 7: C
Câu 8: B
Câu 9: B
Câu 10: D
a, \(\left(x-158\right):6=20\)
\(x-158=20.6\)
\(x-158=120\)
\(x=120+158\)
\(x=278\)
~~~Hok tốt~~~
a) \(\left(x-158\right):6=20\)
\(\Leftrightarrow x-158=\frac{20}{6}=\frac{10}{3}\)
\(\Leftrightarrow x=\frac{10}{3}+158\)
\(\Leftrightarrow x=\frac{484}{3}\)
Vậy : \(x=\frac{484}{3}\)
b) \(x-1,25.4=2,5\)
\(\Leftrightarrow x-5=2,5\)
\(\Leftrightarrow x=2,5+5\)
\(\Leftrightarrow x=7,5\)
Vậy : \(x=7,5\)
c) \(x+0,25=\frac{43}{4}-\frac{18}{5}\)
\(\Leftrightarrow x+\frac{1}{4}=\frac{143}{20}\)
\(\Leftrightarrow x=\frac{143}{20}-\frac{1}{4}\)
\(\Leftrightarrow x=\frac{69}{10}\)
Vậy : \(x=\frac{69}{10}\)