10 x 100 x 100 x 10 = 1 000 000

tchs mik tchs lại

10 x 100 x 100 x 10=1000000

nhanh chậm cl 

 ;(

10 x 100 x 100 x 10

= 100 x 100 x 100

= 10000 x 100

= 1 000 000

Thay x = 10 vào biểu thức B

B = 1300 + [7( 4.10 + 60) + 11]

= 1300 + [7.100 + 11]

= 1300 + [700 + 11]

= 1300 + 711

= 2011

Vậy B = 2011

\(\dfrac{45}{135}=\dfrac{45:45}{135:45}=\dfrac{1}{3}\)

\(\dfrac{117}{234}=\dfrac{117:117}{234:117}=\dfrac{1}{2}\)

\(\dfrac{1515}{2727}=\dfrac{1515:303}{2727:303}=\dfrac{5}{9}\)

\(\dfrac{232323}{494949}=\dfrac{232323:10101}{494949:10101}=\dfrac{23}{49}\)

\(\left(x-\dfrac{1}{3}\right)+\dfrac{1}{4}=\dfrac{1}{2}\)

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

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

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

\(x=\dfrac{1}{4}+\dfrac{1}{3}\)

\(x=\dfrac{3}{12}+\dfrac{4}{12}\)

\(x=\dfrac{7}{12}\)

\(x-\left(\dfrac{1}{7}+\dfrac{2}{5}\right)=\dfrac{16}{35}\)

\(x-\left(\dfrac{5}{35}+\dfrac{14}{35}\right)=\dfrac{16}{35}\)

\(x-\dfrac{19}{35}=\dfrac{16}{35}\)

\(x=\dfrac{16}{35}+\dfrac{19}{35}\)

\(x=\dfrac{35}{35}\)

\(x=1\)

\(x+\dfrac{3}{7}=\dfrac{2}{5}+\dfrac{3}{10}\)

\(x+\dfrac{3}{7}=\dfrac{4}{10}+\dfrac{3}{10}\)

\(x+\dfrac{3}{7}=\dfrac{7}{10}\)

\(x=\dfrac{7}{10}-\dfrac{3}{7}\)

\(x=\dfrac{49}{70}-\dfrac{30}{70}\)

\(x=\dfrac{19}{30}\)

a ) x + 10 + 10 = 1000 + 10                                                                           

x + 10 + 10 = 1010

x + 10        = 1010 - 10

x + 10       = 1000

x               = 1000 - 10 

x               = 990

Vậy x = 990

b ) x - 10 = 90 

    x        = 90 + 10

    x        = 100 

Vậy x = 100

x + 10 + 10 - 10 = 1000

x + 10 = 1000

        x = 1000 - 10

        x = 990

x - 10 = 90

      x = 90 + 10

      x = 100

x=990

x=100

90 + x = 100

        x = 100 - 90

        x = 10

x - 10 = 90

      x = 90 + 10

     x = 100

x - 90 = 10

      x = 10 + 90

      x = 100

k 

90 + x = 100

x = 100 - 90

x = 10

x - 10 = 90

x = 90 + 10

x = 100

x - 90 = 10

x = 10 + 90

x = 100

90 + x = 100

x = 100 - 90

x = 10

x - 10 = 90

x = 10 + 90

x = 100

x - 90 = 10

x = 10 + 90

x = 100

Xong rùi k nhé

10 + 20 = 50 - x 

30 = 50 - x 

x = 50 - 30

x = 20 

10 + 20 = 50 - x

30 = 50 - x

x = 20

10 + 90 = 10 + x

100 = 10 + x

x = 90

\(10+20=50-x\)

\(30=50-x\)

   \(x=50-30\)

   \(x=20\)

\(10+90=10+x\)

\(100=10+x\)

     \(x=100-10\)

     \(x=90\)

\(\dfrac{x-1}{10}+\dfrac{x-2}{11}+\dfrac{x-3}{12}=\dfrac{x-4}{13}+\dfrac{x-5}{14}+\dfrac{x-6}{15}\)

Dựa vào t/c dãy tỉ số = nhau ta có:

\(\dfrac{x-1+x-2+x-3}{10+11+12}=\dfrac{x-4+x-5+x-6}{13+14+15}\)

\(\dfrac{3x-6}{33}=\dfrac{3x-15}{42}\)

\(42\left(3x-6\right)=33\left(3x-15\right)\)

\(126x-252=99x-495\)

\(126-99x=594-252\)

\(27x=342\)

\(x=\dfrac{38}{3}\)

a) 927 – 10 x 2 = 927 – 20

                   = 907

b) 163 + 90 : 3 = 163 + 30

                   = 193

c) 90 + 10 x 2 = 90 + 20

                   = 110

d) 106 – 80 : 4 = 106 – 20

                   = 86

\(a,\left(x-5\right).\frac{30}{100}=\frac{200x}{100}+5\)

\(\left(x-5\right).\frac{3}{10}=2x+5\)

\(\frac{3x}{10}-\frac{3}{2}=2x+5\)

\(\frac{3}{10}x-2x=\frac{3}{2}+5\)

\(x\left(\frac{3}{10}-2\right)=\frac{13}{2}\)

\(x.\frac{-17}{10}=\frac{13}{2}\)

\(x=\frac{13}{2}:\frac{-17}{10}\)

\(x=\frac{13}{2}\cdot\frac{-10}{17}\)

\(x=\frac{-65}{17}\)

Vậy \(x=\frac{-65}{17}\)

Bài 2:

Ta có:\(\frac{-5x}{21}+\frac{-5y}{21}+\frac{-5z}{21}=\frac{-5}{21}\left(x+y+z\right)\)

Mà đề bài cho \(x+y=-z\Rightarrow\frac{-5}{21}\left(-z+z\right)=\frac{-5}{21}.0=0\Rightarrow A=0\)

Vậy \(A=0\)