\(A=\left\{...;0;2;4;6;8;10;12;14;16;18\right\}\)

A = { x | x chia hết cho 2 | x < 20 }

A = {0; 2; 4; 6; 8; 10; 12; 14; 16; 18}

A = { x = 2k|k ϵN; 0≤k≤9}

tập A là tập có 10 phần tử 

\(\left(315.4+5-315\right):3^{16}\)

\(=\left(1260+5-315\right):3^{16}\)

\(=\dfrac{950}{3^{16}}\)

\(\left(315.4+5-315\right):3^{16}\)

\(=\left(1260+5-315\right):3^{16}\)

\(=\left(1265-315\right):3^{16}\)

\(=950:3^{16}\)

\(=\dfrac{950}{3^{16}}\)

Tập hợp các số có ba chữ số khác nhau lấy từ tập `H` gọi là tập `K`

  `=>K={256;265;526;562;625;652}`

x thuộc {256;265;526;562;625;652}

\(\dfrac{-8}{3}.\dfrac{2}{11}-\dfrac{8}{3}:\dfrac{11}{9}\)

\(=\dfrac{-8}{3}.\dfrac{2}{11}-\dfrac{8}{3}.\dfrac{9}{11}\)

\(=\dfrac{-8}{3}.(\dfrac{2}{11}+\dfrac{9}{11})\)

\(=\dfrac{-8}{3}.\dfrac{11}{11}=\dfrac{-8}{3}\)

=-8/3.2/11-8/3.9/11

=-8/3(2/11+9/11)

=-8/3.11/11

=-8/3

\(\dfrac{-3}{10}-0,125+\dfrac{-7}{10}+1,125\)

\(=(\dfrac{-3}{10}+\dfrac{-7}{10})+(-0,125+1,125)\)

\(=\dfrac{-10}{10}+1\)

\(=-1+1=0\)

`(-3)/10 - 0,125 + (-7)/10 + 1,125`

`=(-3)/10- 1/8 -7/10 + 9/8`

`=(3/10 - 7/10) + (-1/8 + 9/8)`

`=-10/10 + 8/8`

` = -1 + 1`

`=0`

\(\dfrac{1}{4}:(10,3-9,8)-\dfrac{3}{4}\)

\(=\dfrac{1}{4}:0,5-\dfrac{3}{4}\)

\(=\dfrac{1}{2}-\dfrac{3}{4}=\dfrac{-1}{4}\)

`1/4 : (10,3 - 9,8) - 3/4`

`=1/4:0,5 - 3/4`

`=1/4:1/2-3/4`

`=1/4xx2-3/4`

`=1/2-3/4`

`=2/4-3/4`

`=-1/4

\(\left(1989.1990+3978\right):\left(1992.1991-3984\right)\)

\(=\left(1989.1990+1989.2\right):\left(1992.1991-1992.2\right)\)

\(=\left[1989.\left(1990+2\right)\right]:\left[1992.\left(1991-2\right)\right]\)

\(=\left[1989.1992\right]:\left[1992.1989\right]\)

\(=1\)

\(\left(637.527-189\right):\left(526.637+448\right)\)

\(=\left[637.\left(526+1\right)-189\right]:\left(526.637+448\right)\)

\(=\left[637.526+448\right]:\left(526.637+448\right)\)

\(=1\)

25.8.50.47.125.4.2

= (25.4) . (8.125) . (50.2) . 47

= 100.1000.100.47

= 10000000.47

= 470000000

25.8.50.47.125.4.2

=> (25.4) . (8.125) . (50.2) . 47

=> 100.1000.100.47

=> 10000000.47

=> 470000000

a, \(-\dfrac{13}{10}x=-\dfrac{5}{2}\Leftrightarrow x=\dfrac{5}{2}:\dfrac{13}{10}=\dfrac{25}{13}\)

b, đk x khác 5 

\(7x-7=6x-30\Leftrightarrow x=-23\)(tm)

\(a)\dfrac{1}{2}x+\dfrac{7}{6}=\dfrac{9}{5}x-\dfrac{4}{3}\)

\(\Leftrightarrow\dfrac{1}{2}x-\dfrac{9}{5}x=-\dfrac{4}{3}-\dfrac{7}{6}\)

\(\Leftrightarrow-\dfrac{13}{10}x=-\dfrac{5}{2}\)

\(\Leftrightarrow x=\dfrac{25}{13}\)

\(b)\dfrac{x-1}{x-5}=\dfrac{6}{7}\)

Điều kiện: \(x\ne5\)

\(\Rightarrow7\left(x-1\right)=6\left(x-5\right)\)

\(\Leftrightarrow7x-7=6x-30\)

\(\Leftrightarrow x=-23\)