a) \(\dfrac{7}{5}x\div\left(9-6\dfrac{13}{21}\right)=2\dfrac{13}{25}\)

\(\dfrac{7}{5}x\div\left(9-\dfrac{139}{21}\right)=\dfrac{63}{25}\)

\(\dfrac{7}{5}x\div\dfrac{50}{21}=\dfrac{63}{25}\)

\(\dfrac{7}{5}x=6\)

\(x=\dfrac{30}{7}\)

b) \(\left(1,16-x\right)\times5,25\div\left(10\dfrac{5}{9}-7\dfrac{1}{4}\right)\times2\dfrac{2}{17}=75\%\)

\(\left(1,16-x\right)\times5,25\div\left(\dfrac{95}{9}-\dfrac{29}{4}\right)\times\dfrac{36}{17}=\dfrac{75}{100}\)

\(\left(1,16-x\right)\times5,25\div\dfrac{119}{36}=\dfrac{17}{48}\)

\(\left(1,16-x\right)\times5,25=\dfrac{2023}{1728}\)

\(1,16-x=\dfrac{289}{1296}\)

\(x=0,9370061728\)

52 ×.(y : 78) = 3380

         y : 78   = 3380 : 52

         y : 78   = 65

         y           = 65 ×. 78

         y           = 5070

Câu 1:

16 - 18|x| = - 8 - 14|x|

18|x| - 14|x| = 16 + 8

4|x| = 24

|x| = 24 : 4

|x| = 6

x = - 6 hoăc x = 6

Vậy x ∈ {-6; 6}

e) 15-3|4x +2| = 3

3|4x + 2| = 15 - 3

3|4x + 2| = 12

|4x + 2| = 12 : 3

|4x + 2| = 4

4x + 2 = -4 hoặc 4x + 2 = 4

Th1: 4x + 2 = - 4

4x = - 4 - 2

4x = - 6

x = - 6/4

x = - 3/2

Th2: 4x + 2 = 4

4x = 4 - 2

4x = 2

x = 2/4

x = 1/2

Vậy x ∈ {- 3/2; 1/2}

a) 2/3 + 11/3 = 13/3

b) 4/5 - 2/3 = 12/15 - 10/15 = 2/15

c) 21/9 x 3/4 = 7/3 x 3/4 = 21/12 = 7/4

d) 6/5 : 6/9 = 6/5 x 9/6 = 54/30 = 9/5

chúc bạn học tốt!

Câu 1:

16 - 18|x| = - 8 - 14|x|

18|x| - 14|x| = 16 + 8

4|x| = 24

|x| = 24 : 4

|x| = 6

x = - 6 hoăc x = 6

Vậy x ∈ {-6; 6}

b,5./x/+7.(2/x/-3)=4.(/x/-4)+25

5|x| + 14|x| - 21 = 4|x| - 16 + 25

19|x| - 21 = 4|x| - 16 + 25

19|x| - 4|x| = 21 - 16 + 25

15|x| = 5 + 25

15|x| = 30

|x| = 30 : 15

|x| = 2

x = - 2 hoặc x = 2

Vậy x ∈ {-2; 2}

\(\dfrac{3\times4\times2\times14}{7\times4\times6}=\dfrac{3\times4\times2\times2\times7}{7\times4\times6}=\dfrac{6\times4\times2\times7}{7\times4\times6}=2\\ \dfrac{21\times18\times3\times4}{2\times6\times7\times9}=\dfrac{3\times7\times9\times2\times3\times2\times2}{2\times6\times7\times9}=\dfrac{3\times2}{1}=6\)

A= 2/5 - 1

= -3/5

B= -30/24 + 4/24 - 36/24 

= 31/12

A = 3/7 x 2x7/3x5 - 3x6/7x3 x 7/6 = 2/5 - 3/3 = 2/5 - 5/5 = -3/5

B=1/6 - (5/4 + 3/2) = 1/6 -(5/4 + 6/4)= 1/6 - 11/4 = 2/12 - 33/12   = - 21/12

a=5,25h31,5p

b=42,5p

c=300 p

h=giờ

p=phút

k mk đi

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