\(\frac{25-x}{56}=\frac{6}{16}\)

\(\frac{25-x}{56}=\frac{3}{8}\)

\(\frac{25-x}{56}=\frac{21}{56}\)

\(\Rightarrow25-x=21\)

\(\Rightarrow x=25-21\)

\(\Rightarrow x=4\)

Vậy x=4

=>(25-x)16=6x56=280

25-x=17.5

x=7.5=15/2

vậy x=15/2

ta giản ước : 6/16 = 3/8 như vậy, ta có :

\(\frac{25-x}{56}=\frac{3}{8}\)

quy đồng 2 phân số cho nhau : ( mẫu số chung ) = 56

ta có : 56 : 8 = 7

\(\frac{3x7}{8x7}=\frac{21}{56}\)

bây giờ, bài toán sẽ như sau :

\(\frac{25-x}{56}=\frac{21}{56}\)

vậy, x = 25 - 21 = 4

k mk nha

chúc bạn học giỏi

Theo đề ta có: \(\frac{25-x}{56}=\frac{6}{16}\)

Ta rút gọn: \(\frac{25-x}{56}=\frac{3}{8}\)

\(\Leftrightarrow\)25 -x . 8 = 56 . 3

\(\Rightarrow\)25 - x . 8 = 168​

\(\Rightarrow\)25 - x      = 168 : 8​

\(\Rightarrow\)25 - x      = 21

\(\Rightarrow\)     - x     = 21 - 25

\(\Rightarrow\)     - x     =  -4

\(\Rightarrow\)       x = 4

Vậy x = 4.

đây là toán lớp 6 nè

lớp 5 mà

25 - x / 56 = 6/16

( 25 - x ) : 56 = 6/16

25 - x = 6/16 x 56

25 - x = 21

      x = 25 - 21

      x = 4

\(\frac{25-x}{56}=\frac{6}{16}\)

\(\frac{x}{56}=25-\frac{6}{16}\)

\(\frac{x}{56}=24\frac{5}{8}\)

\(\frac{x}{56}=24\frac{35}{56}\)

\(\frac{x}{56}=\frac{24\cdot56+35}{56}\)

\(\frac{x}{56}=\frac{1379}{56}\)

Vậy số cần tìm là  \(1379\)

25-X= 6x56:16

25-X=21

    X=25-21

    X=4
K cho mình nhé, ai có facebook thì kb với mình luôn nha <3
 

25-x/56 = 6/16

=> 2.(25-x)/112=7.6/112

=> 2.(25-x)= 42

=> 50 - 2x = 42

=> -2x = 50 - 42

=> -2x = 8

=> x = 8:(-2)

=> x = 4

\(\frac{x-2}{12}+\frac{x-2}{20}+\frac{x-2}{30}+\frac{x-2}{42}+\frac{x-2}{56}+\frac{x-2}{72}=\frac{16}{9}\)

\(\left(x-2\right)\cdot\left(\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}\right)=\frac{16}{9}\)

\(\left(x-2\right)\cdot\left(\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}+\frac{1}{8\cdot9}\right)=\frac{16}{9}\)

\(\left(x-2\right)\cdot\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}\right)=\frac{16}{9}\)

\(\left(x-2\right)\cdot\left(\frac{1}{3}-\frac{1}{9}\right)=\frac{16}{9}\)

\(\left(x-2\right)\cdot\left(\frac{3}{9}-\frac{1}{9}\right)=\frac{16}{9}\)

\(\left(x-2\right)\cdot\frac{2}{9}=\frac{16}{9}\)

\(x-2=\frac{16}{9}:\frac{2}{9}\)

\(x-2=\frac{16}{9}\cdot\frac{9}{2}\)

\(x-2=8\)

\(x=8+2\)

\(x=10\)

Vậy \(x=10\)

\(\left(x-2\right)\left(\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}\right)=\)\(=\frac{16}{9}\)

\(\left(x-2\right)\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}+\frac{1}{8}-\frac{1}{9}\right)=\frac{16}{9}\)

\(\left(x-2\right)\left(\frac{1}{3}-\frac{1}{9}\right)=\frac{16}{9}\)

\(\left(x-2\right)\left(\frac{2}{9}\right)=\frac{16}{9}\)

2(x-2)=16

x-2=8

x=10
 

=> x-2.(1/12+1/20+1/30+1/42+1/56+1/72)=16/9

Đặt : Sáng = 1/12+1/20+1/30+1/42+1/56+1/72

=> Sáng = 1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+1/8.9

=> Sáng = 1.(1/3-1/4+1/4-1/5+...+1/8-1/9

=> Sáng = 91.(1/3-1/9)

=> Sáng = 2/9

Thay Sáng vô biểu thức 1/12+1/20+1/30+1/42+1/56+1/72

Ta được :

x-2.2/9=16/9

giờ thì tự làm nha

=> x-2.(1/12+1/20+1/30+1/42+1/56+1/72)=16/9

Đặt : Sáng = 1/12+1/20+1/30+1/42+1/56+1/72

=> Sáng = 1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+1/8.9

=> Sáng = 1.(1/3-1/4+1/4-1/5+...+1/8-1/9

=> Sáng = 91.(1/3-1/9)

=> Sáng = 2/9

Thay Sáng vô biểu thức 1/12+1/20+1/30+1/42+1/56+1/72

Ta được :

x-2.2/9=16/9

giờ thì tự làm nha

Ai k mk mk k lại

=> x-2.(1/12+1/20+1/30+1/42+1/56+1/72)=16/9

Đặt : Sáng = 1/12+1/20+1/30+1/42+1/56+1/72

=> Sáng = 1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+1/8.9

=> Sáng = 1.(1/3-1/4+1/4-1/5+...+1/8-1/9

=> Sáng = 91.(1/3-1/9)

=> Sáng = 2/9

Thay Sáng vô biểu thức 1/12+1/20+1/30+1/42+1/56+1/72

Ta được :

x-2.2/9=16/9

ta có:$\frac{x-1}{12}+\frac{x-1}{20}+\frac{x-1}{30}+\frac{x-1}{42}+\frac{x-1}{56}+\frac{x-1}{72}=\frac{16}{9}$

 => x+1(1/12+1/20+1/30+1/42+1/56+1/72)=16/9

=> x+1.2/9=16/9

=> x+1 = (16/9):(2/9)

=> x+1 = 8

=> x = 9

thông cảm mình ko đánh được dấu ngoặc tròn

[x-1].[1/12+1/20+1/30+1/42+1/56+1/72] =16/9

[x-1].[1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+1/8.9]=16/9

[x-1].[1/3-1/9]=16/9

[x-1].2/9=16/9

x-1=16/9:2/9

x-1=8 

x=7 

Vậy x=7

Cô bé ngốc ngếch làm sai rùi. x-1 không phải x+1 nha !