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120 - { 300: [ 40 - (2.562 - 262.5)] + 10}
= 120 - { 300 : [ 40 - (-186)] + 10}
= 120 - {300 : 226 + 10}
= 120 - \(\dfrac{1280}{113}\)
= \(\dfrac{12280}{113}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a =143
b = 2510
c 28 x 73 = 2044
cái câu c tính nhẩm chết liền
d [ 1700 - 340 +17 ] : 17 = 81
2 . Tìm x
a 7 . [ x - 3 ] - 6 = 1
7 . [ x - 3 ] = 1+6
7 . [ x - 3 ] = 7
x - 3 = 7 : 7
x - 3 =1
x=3+1=4
b
[x+5] .2:11=6
[x+5] x 2 = 6 x 11
[ x + 5 ] x 2 = 66
x+2=66:2
x+2=33
x=33-2=31
Bài 1
a, \(45+98=143\)
b, \(2605-95=2510\)
c,\(28.73+28\)
\(=28.\left(73+1\right)\)
\(=28.74\)
\(=2072\)
d,\(\left[1700-340+17\right]:17\)
\(=1700:17-340:17+17:17\)
\(=100-20+1\)
\(=81\)
Bài 2
a, \(7.\left(x-3\right)-6=1\)
\(\Leftrightarrow7.\left(x-3\right)=7\)
\(\Leftrightarrow x-3=1\)
\(\Leftrightarrow x=4\)
b, \(\left(x+2\right).2:11=6\)
\(\Leftrightarrow\left(x+2\right).2=66\)
\(\Leftrightarrow x+2=33\)
\(\Leftrightarrow x=31\)
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a) \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}\)
\(\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}\)
b) \(\dfrac{39}{7}:x=13\)
\(x=\dfrac{\dfrac{39}{7}}{13}=\dfrac{3}{7}\)
c) \(\left(\dfrac{14}{5}x-50\right):\dfrac{2}{3}=51\)
\(\dfrac{14}{5}x-50=51\cdot\dfrac{2}{3}=34\)
\(\dfrac{14}{5}x=34+50=84\)
\(x=\dfrac{84}{\dfrac{14}{5}}=30\)
d) \(\left(x+\dfrac{1}{2}\right)\left(\dfrac{2}{3}-2x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\\dfrac{2}{3}-2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)
e) \(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{12}\)
\(\dfrac{1}{6}x=\dfrac{5}{12}\)
\(x=\dfrac{5}{12}:\dfrac{1}{6}=\dfrac{5}{2}\)
g) \(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\dfrac{11}{5}-\dfrac{3}{7}=-2\)
\(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)
\(x\cdot\dfrac{44}{7}+\dfrac{3}{7}=-\dfrac{11}{7}:\dfrac{11}{5}=-\dfrac{5}{7}\)
\(\dfrac{44}{7}x=-\dfrac{5}{7}-\dfrac{3}{7}=-\dfrac{8}{7}\)
\(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)
h) \(\dfrac{13}{4}x+\left(-\dfrac{7}{6}\right)x-\dfrac{5}{3}=\dfrac{5}{12}\)
\(\dfrac{25}{12}x-\dfrac{5}{3}=\dfrac{5}{12}\)
\(\dfrac{25}{12}x=\dfrac{5}{12}+\dfrac{5}{3}=\dfrac{25}{12}\)
\(x=1\)
Mỏi tay woa bn làm nốt nha!!
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\(a,3x+17x=340\)
\(x\left(17+3\right)=340\)
\(x20=340\)
\(x=340:20=17\)
\(b,\left|2x+1\right|=3\\ \Rightarrow\left[{}\begin{matrix}2x+1=3\\2x+1=-3\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}2x=3-1=2\\2x=-3-1=-4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=1\\x=-2\end{matrix}\right.\)
\(c,3^x+3^{x+1}+3^{x+2}=1053\\ 3^x\left(1+3+9\right)=1053\\ 3^x.13=1053\\ 3^x=1053:13=81=3^4\\ \Rightarrow x=4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\left(2x-5\right)+17=6\\ \Rightarrow2x-5=-11\\ \Rightarrow2x=-6\\ \Rightarrow x=-3\\ b,10-2\left(4-3x\right)=-4\\ \Rightarrow2\left(4-3x\right)=14\\ \Rightarrow4-3x=7\\ \Rightarrow3x=-3\\ \Rightarrow x=-1\\ c,24:\left(3x-2\right)=-3\\ \Rightarrow3x-2=-8\\ \Rightarrow3x=-6\\ \Rightarrow x=-2\\ d,5-2x=-17+12\\ \Rightarrow5-2x=-5\\ \Rightarrow2x=10\\ \Rightarrow x=5\)
a: =>2x-5=-11
=>2x=-6
hay x=-3
b: =>2(4-3x)=14
=>4-3x=7
=>3x=-3
hay x=-1
c: =>3x-2=-8
=>3x=-6
hay x=-2
![](https://rs.olm.vn/images/avt/0.png?1311)
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\(3.5^2-64:2^3\)
\(\Leftrightarrow75-8\)
\(\Rightarrow67\)
\(17.81+19.17+210\)
\(\Leftrightarrow17.\left(81+19\right)+210\)
\(\Leftrightarrow17.100+210\)
\(\Leftrightarrow1700+210\)
\(\Leftrightarrow1910\)
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Tìm số nguyên x, biết:
1) -16 + 23 + x = - 16
7+x=-16
x=-16-7
x=-23
2) 2x – 35 = 15
2x=15+35
2x=50
x=50:2
x=25
3) 3x + 17 = 12
3x=12-17
3x=-5
x=-5/3
4) (2x – 5) + 17 = 6
2x-5=6-17
2x-5=-11
2x=-11+5
2x=-6
x=-6:2
x=-3
5) 10 – 2(4 – 3x) = -4
2(4-3x)=10-(-4)
2(4-3x)=14
4-3x=14:2
4-3x=7
3x=4-7
3x=-3
x=-3:3
x=-1
6) - 12 + 3(-x + 7) = -18
3(-x+7)=-18-(-12)
3(x+7)=-6
x+7=-6:3
x+7=-2
x=-2-7
x=-9
ta có
\(3x.4+\left(17-9\right).x=340\)
\(\Leftrightarrow12x+8x=340\Leftrightarrow20x=340\Leftrightarrow x=\frac{340}{20}=17\)
cảm ơn bn nha