a) 36 + 12 + 14 + 38 = (36 + 14) + (12 + 38)

                                 = 50 + 50

                                 = 100

b) 2 x 3 x 5 000 = (2 x 5 000) x 3

                          = 10 000 x 3

                          = 30 000

c) 9 x 13 + 9 x 7 = 9 x (13 + 7)

                          = 9 x 20

                          = 180

a) \(\dfrac{7}{9}\times\dfrac{13}{25}\times\dfrac{9}{7}=\left(\dfrac{7}{9}\times\dfrac{9}{7}\right)\times\dfrac{13}{25}=1\times\dfrac{13}{25}=\dfrac{13}{25}\)

b) \(\dfrac{5}{9}\times\dfrac{21}{25}+\dfrac{21}{25}\times\dfrac{4}{9}\)

\(=\dfrac{21}{25}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\)

\(=\dfrac{21}{25}\times1=\dfrac{21}{25}\)

c) \(\dfrac{19}{5}\times\dfrac{11}{16}-\dfrac{9}{5}\times\dfrac{11}{16}\)

\(=\dfrac{11}{16}\times\left(\dfrac{19}{5}-\dfrac{9}{5}\right)\)

\(=\dfrac{11}{16}\times2=\dfrac{22}{16}=\dfrac{11}{8}\)

90:5+110:5=(90+110):5

                 =200:5

                 =40

HT

90:5+110:5                                 90:5+110:5

= (90+110) : 5                            = 18 + 22

= 200         : 5                            =  40

= 40

= 4/5 x (2/7 + 5/7)

= 4/5 x 1

= 4/5

= 4/5

( 4/5 + 4/5 ) x ( 2/7 + 5/7 )

=    8/5        x          1

=      8/5

\(1,\\ c,\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\dfrac{17\times7-3\times6-5\times7}{6\times7}=\dfrac{119-18-35}{42}=\dfrac{66}{42}=\dfrac{11}{7}\\ 2,\\ a,\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\\ =\dfrac{6:3}{9:3}+\dfrac{7+3}{15}\\ =\dfrac{2}{3}+\dfrac{10}{15}\\ =\dfrac{2}{3}+\dfrac{2}{3}\\ =\dfrac{2+2}{3}=\dfrac{4}{3}\)

\(b,\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\\ =\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\\ =\dfrac{7}{2}+\dfrac{29-11}{12}\\ =\dfrac{7}{2}+\dfrac{18}{12}\\ =\dfrac{7}{2}+\dfrac{18:6}{12:6}\\ =\dfrac{7}{2}+\dfrac{3}{2}\\ =\dfrac{7+3}{2}=\dfrac{10}{2}=5\)

\(c,\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\\ =\dfrac{26}{25}-\dfrac{3\times5}{5\times5}-\dfrac{2\times5}{5\times5}\\ =\dfrac{26-15-10}{25}\\ =\dfrac{1}{25}\)

Bài 1:
\(\dfrac{17}{6}-\dfrac{3}{7}-\dfrac{5}{6}=\left(\dfrac{17}{6}-\dfrac{5}{6}\right)-\dfrac{3}{7}=2-\dfrac{3}{7}=\dfrac{14}{7}-\dfrac{3}{7}=\dfrac{11}{7}\)
Bài 2:
a/\(\dfrac{6}{9}+\dfrac{3}{15}+\dfrac{7}{15}\)
\(=\dfrac{2}{3}+\left(\dfrac{3}{15}+\dfrac{7}{15}\right)\)
\(=\dfrac{2}{3}+\dfrac{2}{3}\)
\(=\dfrac{4}{3}\)
b/\(\dfrac{7}{2}+\dfrac{29}{12}-\dfrac{11}{12}\)
\(=\dfrac{7}{2}+\left(\dfrac{29}{12}-\dfrac{11}{12}\right)\)
\(=\dfrac{7}{2}+\dfrac{3}{2}\)
\(=5\)
c/\(\dfrac{26}{25}-\dfrac{3}{5}-\dfrac{2}{5}\)
\(=\dfrac{26}{25}-\left(\dfrac{3}{5}+\dfrac{2}{5}\right)\)
\(=\dfrac{26}{25}-1\)
\(=\dfrac{26}{25}-\dfrac{25}{25}\)
\(=\dfrac{1}{25}\)
#Đang Bận Thở

264,14 : 0,25 : 4

= 264,14 : ( 0,25 x 4 )

= 264,14 : 1

= 264,14 

36,45 : 0,2 x 2 : 5

=  36,45 : ( 2 x 5 ) : 0,2

= 36,45 : 10 : 0,2 

= 3,645 : 0,2

= 18,225

Tính bằng cách thuận tiện:

a. 264,14 : 0,25 : 4

=264,14

b. 36,45 : 0,2 x 2 : 5

=72,9

a) \(\frac{5}{6}-\left(\frac{2}{5}+\frac{1}{3}\right)=\frac{5}{6}-\frac{11}{15}=\frac{1}{10}\)

b) \(\frac{3}{4}-\frac{1}{3}-\frac{1}{6}=\frac{3}{4}-\left(\frac{1}{3}+\frac{1}{6}\right)=\frac{3}{4}-\frac{1}{2}=\frac{1}{4}\)

a, \(\frac{5}{6}-\left(\frac{2}{5}+\frac{1}{3}\right)\)

 \(=\frac{5}{6}-\frac{2}{5}-\frac{1}{3}\)

\(=\frac{25}{30}-\frac{12}{30}-\frac{10}{30}\)

\(=\frac{3}{30}=\frac{1}{10}\)

b. \(\frac{3}{4}-\frac{1}{3}-\frac{1}{6}\)

\(=\frac{3}{4}-\left(\frac{1}{3}+\frac{1}{6}\right)\)

\(=\frac{3}{4}-\frac{9}{18}\)

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

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