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1) (x - 35) - 120 = 0
x - 35 = 120
x = 120 + 35
x = 155
2) 310 - (118 - x) = 217
118 - x = 310 - 217
118 - x = 93
x = 118 - 93
x = 25
3) 156 - (x + 61) = 82
x + 61 = 156 - 82
x + 61 = 74
x = 74 - 61
x = 13
4) 814 - (x - 305) = 712
x - 305 = 814 - 712
x - 305 = 102
x = 102 + 305 = 407
5) 100 - 7 - (x - 5) = 58
x - 5 = 93 - 58
x - 5 = 35
x = 35 + 5 = 40
6) 12(x - 1) : 3 = 43 + 23
4(x - 1) = 72
x - 1 = 18
x = 18 + 1 = 19
7) 24 + 5x = 75 : 73
24 + 5x = 49
5x = 25
x = 25 : 5 = 5
8) 5(x - 1) : 3 = 43 + 23
\(\dfrac{5}{3}\left(x-1\right)=72\)
x - 1 = \(\dfrac{216}{5}\)
x = 221/5
9) 5(x - 4)2 - 7 = 13
5(x - 4)2 = 20
(x - 4)2 = 4
\(\Rightarrow\left[{}\begin{matrix}x-4=2\\x-4=-2\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=6\\x=2\end{matrix}\right.\)
10) (x + 1) + (x + 2) + ... + (x + 30) = 795
=> (x + x + x + ... + x) + (1 + 2 + 3 +...+ 30) = 795 (1)
Đặt A = 1 + 2 + 3 +...+ 30
Số số hạng trong A là: (30 - 1) : 1 + 1 = 30 (số)
Tổng A bằng : (30 + 1).30 : 2 =465
Thay A = 465 vào (1) , ta được:
30x + 465 = 795
=> 30x =330
=> x =11
1: =>x-35=120
=>x=120+35=155
2: =>118-x=310-217=93
=>x=118-93=25
3: =>x+61=156-82=74
=>x=74-61=13
4: =>x-305=814-712=102
=>x=102+305=407
5: =>93-(x-5)=58
=>x-5=35
=>x=40
6: =>4(x-1)=64+8=72
=>x-1=18
=>x=19
7: =>5x+24=49
=>5x=25
=>x=5
8: =>5(x-1):3=4^3+2^3=64+8=72
=>5(x-1)=216
=>x-1=216/5
=>x=221/5
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (x + 1,2) : 2,5 = 5
x + 1,2 = 5 . 2,5
x + 1,2 = 12,5
x = 12,5 - 1,2
x = 11,3
Vậy x = 11,3
\(b)4,25.x=53,38\)
\(x=53,38:4,25\)
\(x=12,56\)
Vậy x = 12,56
\(c)x.\frac{1}{2}+\frac{3}{4}=1\)
\(x.\frac{1}{2}=1-\frac{3}{4}\)
\(x.\frac{1}{2}=\frac{1}{4}\)
\(x=\frac{1}{4}:\frac{1}{2}\)
\(x=\frac{1}{2}\)
Vậy \(x=\frac{1}{2}\)
\(d)\frac{2}{7}+\frac{5}{7}:x=5-\frac{1}{7}\)
\(\frac{2}{7}+\frac{5}{7}:x=\frac{34}{7}\)
\(\frac{5}{7}:x=\frac{34}{7}-\frac{2}{7}\)
\(\frac{5}{7}:x=\frac{32}{7}\)
\(x=\frac{5}{7}:\frac{32}{7}\)
\(x=\frac{5}{32}\)
Vậy \(x=\frac{5}{32}\)
e) x - 2448 : 24 = 102
x - 102 = 102
x = 102 + 102
x = 204
Vậy x = 204
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\frac{5}{7}+\frac{2}{3}\right).\frac{7}{11}\)
C1:\(=\frac{29}{21}.\frac{7}{11}=\frac{29}{33}\)(tính trong ngoặc rồi mới nhân)
C2:\(=\frac{5}{7}.\frac{7}{11}+\frac{2}{3}.\frac{7}{11}=\frac{5}{11}+\frac{14}{33}=\frac{29}{33}\)(dùng tính chất phân phối)
Những câu khác bn tự làm nha
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{5}{3}-\frac{1}{3}:\left(1-x\cdot\frac{1}{3}\right)=\frac{7}{6}\)
=> \(\frac{1}{3}:\left(1-x\cdot\frac{1}{3}\right)=\frac{5}{3}-\frac{7}{6}\)
=> \(\frac{1}{3}:\left(1-x\cdot\frac{1}{3}\right)=\frac{1}{2}\)
=> \(\left(1-x\cdot\frac{1}{3}\right)=\frac{1}{3}:\frac{1}{2}=\frac{1}{3}\cdot2=\frac{2}{3}\)
=> \(1-\frac{x}{3}=\frac{2}{3}\)
=> \(\frac{x}{3}=1-\frac{2}{3}=\frac{1}{3}\)
=> x = 1
\(3-\left(x:\frac{1}{2}+\frac{3}{2}\right)-\frac{1}{4}=\frac{1}{2}\)
=> \(3-\left(x:\frac{1}{2}+\frac{3}{2}\right)=\frac{1}{2}+\frac{1}{4}=\frac{3}{4}\)
=> \(x:\frac{1}{2}+\frac{3}{2}=3-\frac{3}{4}=\frac{9}{4}\)
=> \(x:\frac{1}{2}=\frac{9}{4}-\frac{3}{2}\)
=> \(x:\frac{1}{2}=\frac{3}{4}\)
=> \(x=\frac{3}{4}\cdot\frac{1}{2}=\frac{3}{8}\)
\(\frac{5}{3}-\frac{1}{3}:\left(1-x\times\frac{1}{3}\right)=\frac{7}{6}\)
\(\frac{1}{3}:\left(1-x\times\frac{1}{3}\right)=\frac{5}{3}-\frac{7}{6}\)
\(\frac{1}{3}:\left(1-x\times\frac{1}{3}\right)=\frac{1}{2}\)
\(1-x\times\frac{1}{3}=\frac{1}{3}:\frac{1}{2}\)
\(1-x\times\frac{1}{3}=\frac{2}{3}\)
\(x\times\frac{1}{3}=1-\frac{2}{3}\)
\(x\times\frac{1}{3}=\frac{1}{3}\)
\(x=\frac{1}{3}:\frac{1}{3}\)
\(x=1\)
\(3-\left(x:\frac{1}{2}+\frac{3}{2}\right)-\frac{1}{4}=\frac{1}{2}\)
\(3-\left(x:\frac{1}{2}+\frac{3}{2}\right)=\frac{1}{2}+\frac{1}{4}\)
\(3-\left(x:\frac{1}{2}+\frac{3}{2}\right)=\frac{3}{4}\)
\(x:\frac{1}{2}+\frac{3}{2}=3-\frac{3}{4}\)
\(x:\frac{1}{2}+\frac{3}{2}=\frac{9}{4}\)
\(x:\frac{1}{2}=\frac{9}{4}-\frac{3}{2}\)
\(x:\frac{1}{2}=\frac{3}{4}\)
\(x=\frac{3}{4}\times\frac{1}{2}\)
\(x=\frac{3}{8}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a.=\frac{21}{35}+\frac{10}{35}\)
\(=\frac{31}{35}\)
\(b.=\frac{21}{24}-\frac{16}{24}\)
\(=\frac{5}{24}\)
\(c.=\frac{50}{27}\)
\(d.=\frac{1}{3}.\frac{1}{2}\)
\(=\frac{1}{6}\)
a)\(\frac{3}{5}+\frac{2}{7}=\frac{14}{35}+\frac{10}{35}=\frac{24}{35}\)
b)\(\frac{7}{8}-\frac{2}{3}=\frac{21}{24}-\frac{16}{24}=\frac{5}{24}\)
c)\(\frac{10}{9}\times\frac{5}{3}=\frac{10.5}{9.3}=\frac{50}{27}\)
d)\(\frac{1}{3}:2=\frac{1}{3}.\frac{1}{2}=\frac{1}{6}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x + 2/3=9/11
<=> x=9/11-2/3= 5/33
b) x - 3/10=4/15
<=> x=4/15+3/10=17/30
c) X x 1/7=5/6
<=> x=5/6:1/7=35/6
d) x : 3/5=1/6
<=> x=1/6x3/5=1/10
\(a,x+\frac{2}{3}=\frac{9}{11}\)
\(x=\frac{9}{11}-\frac{2}{3}\)
\(x=\frac{5}{33}\)
\(b,x-\frac{3}{10}=\frac{4}{15}\)
\(x=\frac{4}{15}+\frac{3}{10}\)
\(x=\frac{17}{30}\)
\(c,x\cdot\frac{1}{7}=\frac{5}{6}\)
\(x=\frac{5}{6}:\frac{1}{7}\)
\(x=\frac{35}{6}\)
\(d,x:\frac{3}{5}=\frac{1}{6}\)
\(x=\frac{1}{6}\cdot\frac{3}{5}\)
\(x=\frac{1}{10}\)
. là nhân nha
\(\dfrac{5}{7}\times x+\dfrac{2}{5}=\dfrac{2}{3}\\ \dfrac{5}{7}\times x=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10}{15}-\dfrac{6}{15}=\dfrac{4}{15}\\ x=\dfrac{4}{15}:\dfrac{5}{7}=\dfrac{4\times7}{15\times5}=\dfrac{28}{75}\)
Vậy `x=28/75`
`HaNa☘D`
\(\dfrac{5}{7}\times x+\dfrac{2}{5}=\dfrac{2}{3}\)
\(\dfrac{5}{7}\times x=\dfrac{2}{3}-\dfrac{2}{5}\)
\(\dfrac{5}{7}\times x=\dfrac{10}{15}-\dfrac{6}{15}\)
\(\dfrac{5}{7}\times x=\dfrac{4}{15}\)
\(x=\dfrac{4}{15}:\dfrac{5}{7}\)
\(x=\dfrac{4}{15}\times\dfrac{7}{5}\)
\(x=\dfrac{28}{75}\)
#Toru