\(\frac{85}{169}.\frac{72}{17}.\frac{13}{55}=\frac{72}{143}\)

Kết quả là

   \(\frac{72}{143}\)

          Đs...

6/13=6*15/13*15=90/195

x/15=13x/15*13=13x/195

7/13=7*13/15*13=91/195

vi 91 la so lien sau cua 90 suy ra ko the co so nao nam giua theo chuong trinh toan 4 nen x o day ko co truong hop nao ca

5sujujusju

\(\frac{3}{7}< \frac{x}{10}< \frac{4}{7}\)

\(\frac{30}{70}< \frac{7x}{70}< \frac{40}{70}\)

\(\Rightarrow30< 7x< 40\)

\(\Rightarrow x=5\)

Ta có 3/7=30/70

         4/7=40/70

         ?/10=7?/70

=>?=5
 

yêu cầu  là gì

Đáp án :17
 

\(\frac{79}{69}-\frac{88}{91}+\frac{88}{91}-\frac{10}{69}\)

\(=\left(\frac{79}{69}-\frac{10}{69}\right)-\left(\frac{88}{91}-\frac{88}{91}\right)\)

\(=1-0=1\)

\(\frac{79}{69}-\frac{81}{91}+\frac{88}{91}-\frac{10}{69}\)

\(=\frac{88}{91}+\left(\frac{79}{69}-\frac{10}{69}\right)\)

\(=\frac{88}{91}+1\)

\(=\frac{89}{91}\)

\(\frac{115}{73}-\frac{24}{411}+\frac{106}{41}-\frac{42}{73}=3\)

Dấu / là phần nha
115/73 - 24/41 + 106/41 - 42/73
= (115/73 - 42/73) + (106/41 - 24/41)
= 73/73 + 82/41
= 1 + 2
= 3

\(\frac{8}{9}\div b=\frac{4}{10}\)

\(\frac{8}{9}\div b=\frac{2}{5}\)

            \(b=\frac{8}{9}\div\frac{2}{5}\)

            \(b=\frac{20}{9}\)

b=8/9:2/5 b=8/9×5/2=20/9

z cko mk xl nhìu nha Trinh Tai Nguyen