\(A=\frac{9}{15.18}+\frac{9}{18.21}+.....+\frac{9}{89.92}\)

\(A=3.\left(\frac{3}{15.18}+\frac{3}{18.21}+....+\frac{3}{89.92}\right)\)

\(A=3.\left(\frac{1}{15}-\frac{1}{18}+\frac{1}{18}-\frac{1}{21}+......+\frac{1}{89}-\frac{1}{92}\right)\)

\(A=3.\left(\frac{1}{15}-\frac{1}{92}\right)\)

\(A=3.\frac{77}{1380}=\frac{77}{460}\)

$A=\frac{9}{15.18}+\frac{9}{18.21}+.....+\frac{9}{89.92}$

$A=3.\left(\frac{3}{15.18}+\frac{3}{18.21}+....+\frac{3}{89.92}\right)$

$A=3.\left(\frac{1}{15}-\frac{1}{18}+\frac{1}{18}-\frac{1}{21}+......+\frac{1}{89}-\frac{1}{92}\right)$

a: \(=\dfrac{18}{51}\cdot\dfrac{34}{9}\cdot\dfrac{17}{18}=\dfrac{17}{51}\cdot\dfrac{34}{9}=\dfrac{1}{3}\cdot\dfrac{34}{9}=\dfrac{34}{27}\)

b: \(=\dfrac{21}{32}\cdot\dfrac{4}{7}\cdot25\cdot\dfrac{4}{5}=\dfrac{21}{7}\cdot\dfrac{4}{32}\cdot20=60\cdot\dfrac{1}{8}=\dfrac{15}{2}\)

=>x/7=-4/7

=>x=-4

a: \(=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{18}{21}+\dfrac{3}{21}\right)+\dfrac{19}{32}+\dfrac{13}{32}=1+1+1=3\)

b: \(=35\cdot1.1\cdot25\cdot\left(7,5-7,5\right)=0\)

a: =(34+14)+(1821+321)+1932+1332=1+1+1=3=(43​+41​)+(2118​+213​)+3219​+3213​=1+1+1=3

b: $=35\cdot 1.1\cdot 25\cdot \left(7,5-7,5\right)=0$

x-(18+21+x):3=5

x-(18+21+x)=5.3

x-(18+21+x)=15

x-18-21-x=15

x-x=15+18+21

x=54

Vậy x=54

Thu phuong yêu hải xuoi doi

=>6/5>x>21/37

hay x=1

x=1

1

\(x-7=-15+21\\ \Rightarrow x=-15+21+7\\ \Rightarrow x=13\)

Vậy \(x=3\)

\(8-x=-18+36\\ \Rightarrow-x=-18+36-8\\ \Rightarrow-x=10\\ \Rightarrow x=-10\)

Vậy \(x=-10\)

x - 7 = -15 + 21                              8 - x = -18 + 36

x - 7 = 6                                         8 - x = 18 

x      = 7 + 6                                        x = 8 - 18

x      = 13                                             x = -10 

mk làm đúng ko ?

\(x-\dfrac{21}{12}=\dfrac{4}{18}\)

\(x=\dfrac{4}{18}+\dfrac{21}{12}\)

\(x=\dfrac{71}{36}\)

d) x - 21/12 = 4/18
    x             = 4/18 + 21/12
    x             = 71/36

71/36