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2/2/17 x 1/1/24 x 5/2/5 x 3/7/9 x 2
36/17 x 25/24 x 27/5 x 34/9 x 2
36 x 25 x 27 x 34 x 2/17 x 24 x 5 x 9
1652400/18360=90
a) 3+2*x=15
2x=15-3
2x=12
x=12:2
x=6
Vậy x=6
b) 24-x=19
x=24-19
x=5
Vậy x=5
c) 29x-13=45
29x=45+13
29x=58
x=58:29
x=2
Vậy x=2
d) 5x-17=38
5x=38+17
5x=55
x=55:5
x=11
Vậy x=11
e) 50-2(x+1)=20
2(x+1)=50-20
2(x+1)=30
x+1+30/2
x+1=15
x=15-1=14
Vậy x=14
f)
123,45 + 23,56 +76,44 + 54,55
= (123,45 + 54,55) + (23,56 + 76,44)
= 178 + 100
= 278
456 x 45 + 456 x 10 + - 456 x 55
=456 x (45 +10-55)
=456 x 0
=0
2,5 x 8,5 + 7,5 x 8,5
=8,5 x (2,5 +7,5)
= 8,5 x 10
= 85
86 x 5 + 86 x 4 + 86
= 86 x (5+4+1)
= 86 x10
860
a) = 29/15
b) = 7/15
c) = 1
d) = 3
e) = 67/17
f) = 2
mk nhanh nhất tk cho mk nha
a/\(\frac{3}{5}+\frac{4}{3}=\frac{9}{15}+\frac{20}{15}=\frac{29}{15}\)
b/\(\frac{2}{3}-\frac{1}{5}=\frac{10}{15}-\frac{3}{15}=\frac{7}{15}\)
c/\(\frac{1}{2}+\frac{1}{3}+\frac{1}{6}=\frac{3}{6}+\frac{2}{6}+\frac{1}{6}=\frac{7}{6}\)
d,\(\frac{3}{5}+\frac{4}{7}+\frac{7}{5}+\frac{3}{7}=\left(\frac{3}{5}+\frac{7}{5}\right)+\left(\frac{4}{7}+\frac{3}{7}\right)=2+1=3\)
a) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3
c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21
A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3
c) TƯƠNG TỰ CÂU A VÀ B
* HOKTOT*
NHA
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
Câu 2:
\(\dfrac{7}{9}\cdot\dfrac{3}{35}=\dfrac{1}{5}\cdot\dfrac{1}{3}=\dfrac{1}{15}\)
\(\dfrac{9}{22}\cdot55=\dfrac{9\cdot55}{22}=\dfrac{9\cdot5}{2}=\dfrac{45}{2}\)
\(1\dfrac{2}{24}\times5\dfrac{2}{5}\times2\times3\dfrac{7}{9}\times2\times\dfrac{2}{17}\)
\(=\dfrac{13}{12}\text{x}\dfrac{27}{5}\text{x}2\text{x}\dfrac{34}{9}\text{x}2\text{x}\dfrac{2}{17}\)
\(=\dfrac{13}{5}\text{x}\dfrac{27}{12}\text{x}4\text{x}\dfrac{34}{17}\text{x}\dfrac{2}{9}\)
\(=\dfrac{13}{5}\text{x}\dfrac{9}{4}\text{x}4\text{x}\dfrac{4}{9}\)
\(=\dfrac{13}{5}\text{x}4=\dfrac{52}{5}\)
\(2\dfrac{2}{17}\text{x}1\dfrac{1}{24}\text{x}5\dfrac{2}{5}\text{x}3\dfrac{7}{9}\text{x}2\)
\(=\dfrac{36}{17}\text{x}\dfrac{25}{24}\text{x}\dfrac{27}{5}\text{x}\dfrac{34}{9}\text{x}2\)
\(=\dfrac{34}{17}\text{x}\dfrac{36}{9}\text{x}\dfrac{25}{5}\text{x}\dfrac{27}{24}\text{x}2\)
\(=2\text{x}4\text{x}5\text{x}\dfrac{27}{12}=40\text{x}\dfrac{9}{4}=90\)