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a) \(12+\frac{x}{42}=\frac{5}{6}\)
\(\frac{x}{42}=\frac{5}{6}-12\)
\(\frac{x}{42}=\frac{-67}{6}\)
\(\frac{x}{42}=\frac{-469}{42}\)
\(\Rightarrow x=-469\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a.\dfrac{12+x}{42}=\dfrac{35}{42}\Leftrightarrow12+x=35\Leftrightarrow x=23\)
\(b.\dfrac{25-x}{40}=\dfrac{3}{8}\Leftrightarrow\dfrac{25-x}{40}=\dfrac{15}{40}\Leftrightarrow25-x=15\Leftrightarrow x=10\)
\(c.\dfrac{13+x}{20}=\dfrac{3}{4}\Leftrightarrow\dfrac{13+x}{20}=\dfrac{15}{20}\Leftrightarrow13+x=15\Leftrightarrow x=2\)
\(d.\dfrac{23-x}{25}=\dfrac{20}{25}\Leftrightarrow23-x=20\Leftrightarrow x=3\)
đánh dấu x chỉ kết quả đ
a ) 12/48 = 1/3
b . 25/40 = 25 : 5 = 5/8
40 : 5
c .7 x 2 x 6 = 1/5
12 x 7 x 5
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4/7 = 16/28
36/42 = 6/7
5/8 = 25/40 = 30/48
25/15 = 5/3 = 10/6
kick mình nha
![](https://rs.olm.vn/images/avt/0.png?1311)
5/2 lớn hơn 3/7
4/3 lớn hơn.
3/2 lớn hơn.
3/9=1/3
9/12=3/4
8/18=1/4
60/36=10/6
17/34=1/2
17/51=1/3
35/100=7/25
25/100=1/4
8/1000=1/125
24/30=8/10
18/54=1/3
72/42=24/14=12/7
Xin lỗi vì ko giải hết cho cậu nhưng mình phải đi ngủ đây.Hôm sau minh giải mốt phần còn lại cho
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b, 3/5 + 4/7 + 2/8 + 10/25 + 9/21 + 28/16
= 3/5 + 4/7 + 2/8 + 2/5 + 3/7 + 14/8
= (3/5 + 2/5) + ( 4/7 + 3/7) + ( 2/8 + 14/8)
= 1 + 1 + 7/4
= 2 + 7/4 = 15/4
c , 8/7 + 7/6 + 5/8 + 10/12 + 24/28 + 6/16
= c , 8/7 + 7/6 + 5/8 + 5/6 + 6/7 + 1/2
= (8/7 + 6/7) + (7/6 + 5/6) + 5/8 + 1/2
= 14/7 + 12/6 + 5/8 + 1/2
= 2 + 2 + 5/8 + 1/2
= 4 + 9/8 = 41/8
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,12+\frac{x}{42}=\frac{5}{6}\)
\(\Rightarrow\frac{x}{42}=\frac{5}{6}-12\)
\(\Rightarrow\frac{x}{42}=\frac{-67}{6}\)
\(\Leftrightarrow6x=42\times(-67)\)
\(\Leftrightarrow6x=-2814\)
\(\Leftrightarrow x=-2814\div6=-469\)
Vậy x = -469
\(b,25-\frac{x}{40}=\frac{3}{8}\)
\(\frac{x}{40}=25-\frac{3}{8}\)
\(\frac{x}{40}=\frac{197}{8}\)
\(\Leftrightarrow8x=40\times197\)
\(\Leftrightarrow8x=7880\)
\(\Leftrightarrow x=7880\div8=985\)
Vậy x = 985
Chúc bạn học tốt
a, \(12+\frac{x}{42}=\frac{5}{6}\Leftrightarrow\frac{x}{42}=-\frac{67}{6}\Leftrightarrow\frac{x}{42}=\frac{-469}{42}\)
Khử mẫu đi ta đc : \(x=-469\)
b, \(25-\frac{x}{40}=\frac{3}{8}\Leftrightarrow\frac{x}{40}=\frac{197}{8}\Leftrightarrow\frac{x}{40}=\frac{985}{40}\)
Khử mẫu đi ta đc : \(x=985\)