1

a) X=3/5 : 4/5

X=3/4

b) x=2/3 x 2/5

X=4/15

c) x=14/5 : 6/7

X=49/15

d) x=4/9 x 2/3

X= 8/27

2

7/15 < x < 4/3

7/15 < x < 20/15

X = 8/15;9/15;10/15;11/15;12/15;13/15;14/15;15/15;16/15;17/15;18/15;19/15

3

Hai năm nữa tuổi mẹ là

24:(4-1)x4 = 32 (tuổi)

Hai năm nữa tuổi con là

32:4=8 (tuổi)

Năm nay tuổi mẹ là

32-2=30 (tuổi)

Năm nay tuổi con là

8-2=6 (tuổi)

Đáp số tự ghi nhé

1a.\(\frac{3}{4}\)

 b.\(\frac{4}{15}\)

 c.\(\frac{49}{15}\)

 d.\(\frac{8}{27}\)

2. x = 1

3. Mẹ 30 tuổi, con 6 tuổi

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\(\frac{1}{10}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{5}\cdot\frac{5}{4}\cdot\frac{4}{3}\cdot\frac{3}{2}=\frac{1}{10}\)

\(\frac{1}{10}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times\frac{5}{6}\times\frac{6}{5}\times\frac{5}{4}\times\frac{4}{3}\times\frac{3}{2}\)\(\frac{3}{2}\)

\(=\frac{1}{10}\times\left(\frac{2}{3}\times\frac{3}{2}\right)\times\left(\frac{3}{4}\times\frac{4}{3}\right)\times\left(\frac{4}{5}\times\frac{5}{4}\right)\times\left(\frac{5}{6}\times\frac{6}{5}\right)\)

\(=\frac{1}{10}\times1\times1\times1\times1\)

\(=\frac{1}{10}\)

#Chúc bạn học tốt !

#k cho mình nhé ?

Ta có:  4/5:4/7=4/5x7/4=7/5=>7/5>1>0

2/5x10/3=4/3=>4/3>1>0

7/5=42/30

4/3=40/30

Vì: 42/30>41/30>40/30

=>X=41/30

x=41/30 đó bạn k mình nha bạn ^_^

\(a,\frac{5}{6}+x\)x \(\frac{3}{4}=3\)

\(x\)x \(\frac{3}{4}=3-\frac{5}{6}\)

\(x\)x \(\frac{3}{4}=\frac{13}{6}\)

\(x=\frac{13}{6}:\frac{3}{4}\)

\(x=\frac{26}{9}\)

b, \(5\frac{1}{6}-x:\frac{3}{4}=\frac{2}{3}\)

\(\frac{31}{6}-x:\frac{3}{4}=\frac{2}{3}\)

\(x:\frac{3}{4}=\frac{31}{6}-\frac{2}{3}\)

\(x:\frac{3}{4}=\frac{9}{2}\)

\(x=\frac{9}{2}\)x \(\frac{3}{4}\)

\(x=\frac{27}{8}\)

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Thank you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a) \(\dfrac{1}{2}+x=\dfrac{5}{6}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{2}=\dfrac{5}{6}-\dfrac{3}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)

b) \(x+\dfrac{1}{4}=\dfrac{3}{4}\)

\(\Rightarrow x=\dfrac{3}{4}-\dfrac{1}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)

c) \(x-\dfrac{1}{5}=\dfrac{3}{10}\)

\(\Rightarrow x=\dfrac{3}{10}+\dfrac{1}{5}=\dfrac{3}{10}+\dfrac{2}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

d) \(\dfrac{5}{6}-x=\dfrac{1}{3}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{3}=\dfrac{5}{6}-\dfrac{2}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)

e) \(\dfrac{3}{10}+x=\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{1}{2}-\dfrac{3}{10}=\dfrac{5}{10}-\dfrac{3}{10}=\dfrac{2}{10}=\dfrac{1}{5}\)

g) \(x+\dfrac{1}{4}=\dfrac{3}{8}\)

\(\Rightarrow x=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{3}{8}-\dfrac{2}{8}=\dfrac{1}{8}\)

a) 

b) 

c) 

d) 

e) 

g) 

Đọc tiếp

 x = 2 - 3/4

x = 5/4

\(x+\frac{3}{4}=\frac{10}{5}\)

           \(x=\frac{10}{5}-\frac{3}{4}\)

            \(x=\frac{5}{4}\)

cau1 x= 1/2 + 3/4 

x= 5 / 4

cau2 x = 8 x 1/4

x= 2

cau 3 x= 5/12 - 1/6

x = 1/4

cau 4 x = 4/5 - 1/10

x = 7/10

cau5 x= 2/5 : 1/3

x= 6/5

cau6 x =2/3 : 2/7

x = 7/3

x - 3/4 = 1/2 

x = 1/2 + 3/4 

x = 0,875

x : 1/4 = 8 

x = 8 x 1/4

x = 2 

x + 1/6 = 5/12

x = 5/12 - 1/6 

x = 3/12

4/5 - x = 3/10 

x = 4/5 - 3/10 

x = 5/10 = 1/2

2/5 :x =  1/3

x = 2/5 : 3 

x = 2/15

2/7 * x = 2/3

x = 2/3 : 2/7

= 

(1 + x) + (2 + x) + (3 + x) + (4 + x) + (5 + x) = 10.5

15 + 5.x = 50

5.x = 50 - 15

5.x = 35

x = 35 : 5

x = 7

dấu chấm là dấu nhân

(1+x)+(2+x)+(3+x)+(4+x)+(5+x)=10\(\times\)5

=>1+2+3+4+5+5\(\times\)x=50

=>15+5\(\times\)x=50

=>5\(\times\)x=50-15

=>5\(\times\)x=35

=>x=35:5

=>x=7

Vậy x=7

x = 1/2

chúc bạn học tốt ^ _ ^

\(x+\frac{1}{2}=\frac{10}{5}-\frac{5}{5}\)

\(x+\frac{1}{2}=1\)

          \(x=1-\frac{1}{2}\)

          \(x=\frac{1}{2}\)