45-x/3=56/7

x/3= 45-56/7

x/3 = 315-56/ 7

x/3 = 37

x= 37.3

x= 111

ngoài ra còn có cách 45-x/3=56/7 

x/3 = 45-8

x/3 = 37

...

X= 111

Ko còn bài nào giải làm tạm bài này chứ mk cũng ko muốn làm n bài dễ

a)\(45-\frac{x}{3}=\frac{56}{7}\)

\(\Leftrightarrow\frac{x}{3}=45-\frac{56}{7}\)

\(\Leftrightarrow\frac{x}{3}=37\)

\(\Rightarrow x=171\)

b)\(x-\frac{7}{85}=\frac{4}{17}\)

\(\Leftrightarrow x=\frac{4}{17}+\frac{7}{85}\)

     \(\Rightarrow x=\frac{27}{85}\)

a)45—x/3=56/7

45—x/3=8

x/3=45—8

x/3=37

x=37x3

x=111

Trịnh Thành Công đéo xứng làm CTV khi trả lwoif toàn câu dễ 

Ta có : 45 - \(\frac{x}{3}=\frac{56}{7}\)

\(\frac{x}{3}=45-\frac{56}{7}\)

\(\frac{x}{3}=37\)

\(x=37.3\)

\(x=171\)

=144 : (225-270+81) -20

=144 : 36 -20

=4-20

=-16

(X-17).25=(X.5)-68+43

25x - 425 = 5x -25

25x-5x = -25+425

20x = 400

x= 20

48,3 x 2 + 48,3 x 7 + 48,3

= 48,3 x 2 + 48,3 x 7 + 48,3 x 1

= 48,3 x (2 + 7 + 1)

= 48,3 x 10

= 483

48,3 x 2 + 48,3 x 7 + 48,3

= 48,3 x 2 + 48,3 x 7 + 48,3 x 1

= 48,3 x (2 + 7 + 1)

= 48,3 x 10

= 483

48,3.2+48,3.7+48,3

= 48,3.2+48,3.7+48,3.1

=48,3.(2+7+1)

=48,3.10

=483

mink thay dấu nhân thành dấu chấm nha bạn

\(31.x+67=25.\left(x-3\right)+172\)

\(\Leftrightarrow31x+67=25x-75+172\)

\(\Leftrightarrow31x+67=25x+97\)

\(\Leftrightarrow31x-25x=97-67\)

\(\Leftrightarrow6x=30\)

\(\Leftrightarrow x=30:6\)

\(\Leftrightarrow x=5\)

Dấu nhân là dấu chấm nha bạn

\(A=\frac{3}{1.3}+\frac{3}{3.5}+.....+\frac{3}{19.21}\)

\(A=\frac{3}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+......+\frac{2}{19.21}\right)\)

\(A=\frac{3}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+......+\frac{1}{19}-\frac{1}{21}\right)\)

\(A=\frac{3}{2}.\left(1-\frac{1}{21}\right)\)

\(A=\frac{3}{2}.\frac{20}{21}\)

\(A=\frac{10}{7}\)

Ta có:

\(A=\frac{3}{1.3}+\frac{3}{3.5}+\frac{3}{5.7}+...+\frac{3}{19.21}\)

\(\Rightarrow A=\frac{2}{3}.\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{19}-\frac{1}{21}\right)\)

\(\Rightarrow A=\frac{2}{3}.\left(\frac{1}{1}-\frac{1}{21}\right)=\frac{2}{3}.\frac{20}{21}=\frac{40}{63}\)

A = \(\frac{3}{1x3}+\frac{3}{3x5}+\frac{3}{5x7}+.......+\frac{3}{19x21}\)

A : 3 = \(\frac{1}{1x3}+\frac{1}{3x5}+\frac{1}{5x7}+.........+\frac{1}{19x21}\)

A : 3 = \(\frac{1}{1}+\frac{1}{3}-\frac{1}{3}+\frac{1}{5}-\frac{1}{5}+\frac{1}{7}-.........+\frac{1}{19}-\frac{1}{21}\)

=> A : 3 = \(\frac{1}{1}-\frac{1}{21}\)= \(\frac{21}{21}-\frac{1}{21}=\frac{20}{21}\)

=> A = \(\frac{20}{21}x3=\frac{60}{21}=\frac{20}{7}\)

\(\left(x-17\right)\cdot25=\left(x\cdot5\right)-68+43\)

\(\Leftrightarrow25x-425=5x-25\)

\(\Leftrightarrow20x=400\)

\(\Leftrightarrow x=20\)

bạn đúp vòa google nhấn geatesysolution ,nó sẽ giải cho bạn