=(5/12+7/12)*2/3+1/3

=1*2/3+1/3

=2/3+1/3

=1

2/3x(5/12+7/12)+1/3

2/3x       1        +1/3

2/3+1/3

=1              k mik nhaaaaa

5/12×2/3+2/3×7/12+1/3

=2/3×(5/12+7/12)+1/3

=2/3×          1          +1/3

=              2/3           +1/3

=                       1

\(\frac{5}{12}.\frac{2}{3}+\frac{2}{3}.\frac{7}{12}+\frac{1}{3}\)

\(=\frac{2}{3}.\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{1}{3}\)

\(=\frac{2}{3}.\frac{12}{12}+\frac{1}{3}\)

\(=\frac{2}{3}.1+\frac{1}{3}\)

\(=\frac{2}{3}+\frac{1}{3}\)

\(=\frac{3}{3}=1\)

Dấu "." bằng dấu x

nhầm:

5/12x2/3+2/3x7/12++1/3

\(\frac{5}{15}+\frac{3}{12}+\frac{4}{20}+\frac{18}{27}+\frac{12}{16}+\frac{30}{25}\)

\(=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\)

\(=\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{4}+\frac{3}{4}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)

\(=1+1+1\)

\(=3\)

1-(1-(1/2 × 3/5 + 1/5 × 1/2 + 2/10 × 1/2 +1/2)

=1-(1-(3/10 + 1/10 + 1/10 + 5/10)

=1-(1-(3+1+1+5/10)

=1-(1- 10/10)

=1-(1-1)

=1-0

=1

\(1-\left[1-\left(\frac{1}{2}\times\frac{3}{5}+\frac{1}{5}\times\frac{1}{2}+\frac{2}{10}\times\frac{1}{2}+\frac{1}{2}\right)\right]\)

\(=1-\left[1-\left\{\frac{1}{2}\times\left(\frac{3}{5}+\frac{1}{5}+\frac{2}{10}+\frac{1}{2}\right)\right\}\right]\)

\(=1-\left[1-\left\{\frac{1}{2}\times\left(\frac{6}{10}+\frac{2}{10}+\frac{2}{10}+\frac{5}{10}\right)\right\}\right]\)

\(=1-\left[1-\left\{\frac{1}{2}\times\left(\frac{6+2+2+5}{10}\right)\right\}\right]\)

\(=1-\left[1-\left\{\frac{1}{2}\times\frac{3}{2}\right\}\right]\)

\(=1-\left[1-\frac{3}{4}\right]\)

\(=1-\frac{1}{4}\)

\(=\frac{3}{4}\)

\(\frac{2}{3}\cdot\frac{4}{7}+\frac{2}{3}\cdot\frac{3}{7}\)

=\(\frac{2}{3}\left(\frac{4}{7}+\frac{3}{7}\right)\)

=  \(\frac{2}{3}\cdot1\)

=  \(\frac{2}{3}\)

=(1/11 + 4/11) + (3/4 + 1/4)

=5/11 + 4/4

=5/11+1

=5/11+ 11/11

=16/11

\(\frac{1}{11}+\frac{3}{4}+\frac{4}{11}+\frac{1}{4}\)

\(=\left(\frac{1}{11}+\frac{4}{11}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)\)

\(=\frac{5}{11}+1\)

\(=1\frac{5}{11}\)

1/11+3/4+4/11+1/4

=(1/11+4/11)+(3/4+1/4)

=5/11+1

=16/11

 A = 24 x 73 + 12 x 90 - 24 x 18

 A = 24 x 73 + 12 x 2 x 45 - 24 x 18

 A = 24 x 73 + 24 x 45 - 24 x 18

 A = 24 x ( 73 + 45 - 18 )

 A = 24 x 100

A = 2400

19/20x2/100+19/20x2/100

= [19/20+19/20]x2/100

= 38/20x2/100

= 19/500

75/76x102/100-75/76x2/100

= [102/100-2/100]x75/76

= 1x75/76

= 75/76

3x7/10+7/10x5+2x7/10

= [3+5+2]x7/10

= 10x7/10

= 7

giá trị biểu thức 

2/5+2/3x3/4

= 2/5+1/6

= 17/30

1/2x1/3-1/8

= 1/6-1/8

= 1/24

[1/2+1/3]:3/9

= 5/6:3/9

= 5/2

                       nhớ tick cho tớ nhé

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