\(a,x=\dfrac{210}{-35}=-6\\ b,x=\dfrac{42}{-7}=-6\\ c,x=\dfrac{180}{-12}=-15\\ d,x=3-5=-2\)

180 : ( 18 x 5 )

= 180 : 90

= 2

b) 240 : ( 2 x 3 x 4 )

= 240 : 24

= 10

c) 4400 : ( 22 x 35 ) 

= 4400 : 770

= \(\dfrac{40}{7}\)

\(=2,019\left(40+9\right)+20,18.6\)

\(=2,019.49+20,18.6\)

\(=98,931+121,98=220,011\)

KẾT QUẢ LÀ 220,011

Bài 2: 

a: 2/5=14/35

3/7=15/35

b: -3/4=-9/12

-7/-12=7/12

c: 5/9=60/108

-11/-12=11/12=99/108

d: -4/7=-36/63

8/9=56/63

-10/21=-30/63

Bài 2: 

a: 2/5=14/35

3/7=15/35

b: -3/4=-9/12

-7/-12=7/12

c: 5/9=60/108

-11/-12=11/12=99/108

d: -4/7=-36/63

8/9=56/63

-10/21=-30/63

c: 90\(⋮\)x-2

=>\(x-2\in\){1;-1;2;-2;3;-3;5;-5;6;-6;9;-9;10;-10;15;-15;18;-18;30;-30;45;-45;90;-90}

=>x\(\in\){3;1;4;0;5;-1;7;-3;8;-4;11;-7;12;-8;17;-13;20;-16;32;-28;47;-43;92;-88}

mà 10<=x<=90

nên \(x\in\left\{11;12;17;20;32;47\right\}\)

d: \(x⋮12\)

=>\(x\in\left\{0;12;24;36;48;60;72;...\right\}\)

mà 30<=x<=60

nên \(x\in\left\{36;48;60\right\}\)

a: x-140:35=270

=>x-4=270

=>x=270+4=274

b: \(\left(3x-1\right)^2-3^2=4^2\)

=>(3x-1)²-9=16

=>\(\left(3x-1\right)^2=25\)

=>\(\left[{}\begin{matrix}3x-1=5\\3x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=6\\3x=-4\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=2\\x=-\dfrac{4}{3}\end{matrix}\right.\)

a) \(\dfrac{x}{-6}=\dfrac{-15}{45}\)

    \(\dfrac{-x}{6}=\dfrac{-15}{45}\)

    \(\dfrac{x}{6}=\dfrac{15}{45}\)

    \(x=\dfrac{\left(15\cdot6\right)}{45}\)

    \(x=2\)

b) \(\dfrac{x}{5}=\dfrac{16}{25}\)

    \(x=\dfrac{\left(16\cdot5\right)}{25}\)

    \(x=\dfrac{80}{25}\)

   \(x=\dfrac{16}{5}\)

c) \(\dfrac{5}{x-3}=\dfrac{20}{-12}\)

  \(x-3=\dfrac{\left(5\cdot-12\right)}{20}\)

 \(x-3=-3\)

 \(x=\left(-3\right)+3\)

\(x=0\)

d) \(\dfrac{2}{5}\cdot x=\dfrac{6}{35}\)

         \(x=\dfrac{6}{35}\div\dfrac{2}{5}\)

        \(x=\dfrac{3}{7}\)

\(a,\dfrac{x}{7}=\dfrac{6}{21}\Rightarrow x.21=7.6=42\\ \Rightarrow x=2\\ b,\dfrac{1}{2}=\dfrac{x}{12}\Rightarrow1.12=2.x=12\\ \Rightarrow x=6\\ c,\dfrac{-7}{6}=\dfrac{x}{12}\Rightarrow-7.12=6.x=-84\\ \Rightarrow x=-14\)

mình đang cần gấp, giúp mình với ạ

câu d là 6 phần mấy đấy ạ?

a) \(\dfrac{1}{7}< \dfrac{x}{35}< \dfrac{2}{5}\)

\(\Rightarrow\dfrac{5}{35}< \dfrac{x}{35}< \dfrac{14}{35}\)

\(\Rightarrow5< x< 14\)

b) \(\dfrac{5}{13}< 2-x< \dfrac{5}{8}\)

\(\Rightarrow2-\dfrac{5}{8}< x< 2-\dfrac{5}{13}\)

\(\Rightarrow\dfrac{11}{8}< x< \dfrac{21}{13}\)

ai mần tr mình cho tích

a) ta có:\(\dfrac{1}{7}=\dfrac{1.5}{7.5}=\dfrac{5}{35}\);\(\dfrac{2}{5}=\dfrac{2.7}{5.7}=\dfrac{14}{35}\)

\(\Rightarrow x\in\left\{6;7;8;9;10;11;12;13\right\}\)

b)ta có:\(2-x=\dfrac{5}{9};\dfrac{5}{10};\dfrac{5}{11};\dfrac{5}{12}\)

\(\Rightarrow x=2-\dfrac{5}{9};2-\dfrac{5}{10};2-\dfrac{5}{11};2-\dfrac{5}{12}\)

\(\Rightarrow x=\dfrac{13}{9};\dfrac{3}{2};\dfrac{17}{11};\dfrac{19}{12}\)

a) \(x:\frac{2}{3}=150\) 

\(x=150.\frac{2}{3}\) 

\(x=100\) 

b) \(\frac{35}{9}:x=\frac{35}{6}\) 

\(x=\frac{35}{9}.\frac{6}{35}=\frac{2}{3}\) 

c,d tương tự

a )  x : 2/3 = 150                                               c ) x : 4/7 = 180

     x         =    150 x 2/3                                        x         =    180 x  4/7

     x         =       100                                             x         =            720/7

b ) 35/9 : x  = 35/6                                             d )      49/8 : x  = 49/5 

              x  =  35/9 : 35/6                                                      x  =   49/8 : 49/5

             x   =     2/3                                                              x  =   5/8        

a) x : \(\frac{2}{3}\)= 150

   x = 150 x \(\frac{2}{3}\)

   x = 100

b) \(\frac{35}{9}:x=\frac{35}{6}\)

    x = \(\frac{35}{9}\): \(\frac{35}{6}\)

x = \(\frac{2}{3}\)

c) x : 4/7 = 180

x = 180 x 4/7

x = 720/7

d) 49/8 : x = 49/5

x = 49/8 : 49/5

x = 5/8

nhớ k cho mik nha mik đang rất cần cái k của bn