\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)

\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)

\(=\frac{4}{15}.\frac{9}{9}\)

\(=\frac{4}{15}.1\)

\(=\frac{4}{15}\)

\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)

\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)

\(=\frac{13}{19}.\frac{11}{11}\)

\(=\frac{13}{19}.1\)

\(=\frac{13}{19}\)

a)4/15 x(7/9+2/9)=4/15x1=4/15

b)13/19x(23/11-8/11-4/11)13/19x1=13/19

Bằng \(\frac{200}{3}\)

kết quả bằng 200/3

bằng 2 nha

17/11 + 17/15 - 6/11 + 18/15 

= ( 17/11 + 6/11 )  - ( 7/15 + 8/15 ) 

= 21/11 - 15/15 

= 21/11 -1 

= 10/11

\(\frac{19}{15}+\frac{31}{23}-\frac{4}{15}-\frac{8}{23}\)

\(=\left(\frac{19}{15}-\frac{4}{15}\right)+\left(\frac{31}{23}-\frac{8}{23}\right)\)

\(=\frac{15}{15}+\frac{23}{23}\)

\(=1+1=2\)

\(\frac{19}{15}+\frac{31}{23}-\frac{14}{15}-\frac{8}{23}\)

\(=\frac{19}{15}-\frac{4}{15}+\frac{31}{23}-\frac{8}{23}\)

\(=1+1=2\)

chúc bạn học giỏi

\(\frac{11}{30}-\frac{9}{25}\times\frac{15}{27}\)

\(=\frac{11}{30}-\frac{1}{5}\)

\(=\frac{1}{6}\)

\(=\frac{11}{30}-\frac{1}{5}\)

\(=\frac{11}{30}-\frac{6}{30}\)

\(=\frac{5}{30}=\frac{1}{6}\)

Ai thấy tớ đúng k nha

\(=\left(\frac{4}{17}+\frac{13}{17}\right)-\left(\frac{7}{15}+\frac{8}{15}\right)+\left(\frac{10}{16}-\frac{7}{16}\right)\)

\(=1-1+\frac{3}{16}\)

\(\frac{3}{16}\)

gộp 1,3 

2,4

5,6

thì ra 17/17-15/15+3/16=3/16

hk tốt!

\(\frac{12}{18}+\frac{1}{3}+\frac{1}{7}+\frac{2}{8}+\frac{27}{36}+\frac{42}{49}\)

\(=\frac{2}{3}+\frac{1}{3}+\frac{1}{7}+\frac{1}{4}+\frac{3}{4}+\frac{6}{7}\)

\(=\left(\frac{2}{3}+\frac{1}{3}\right)+\left(\frac{1}{7}+\frac{6}{7}\right)+\left(\frac{1}{4}+\frac{3}{4}\right)\)

\(=1+1+1\)

\(=3\)

1.

a) \(\frac{16}{24}-\frac{1}{3}=\frac{16}{24}-\frac{8}{24}=\)\(\frac{8}{24}=\frac{1}{3}\)

b) \(\frac{4}{5}-\frac{12}{60}=\frac{48}{60}-\frac{12}{60}=\frac{36}{60}=\frac{9}{15}\)

3.

a)\(\frac{17}{6}-\frac{2}{6}=\frac{17-2}{6}=\frac{15}{6}\)

b) \(\frac{16}{15}-\frac{11}{15}=\frac{16-11}{15}=\frac{5}{15}=\frac{1}{3}\)

c) \(\frac{19}{12}-\frac{13}{12}=\frac{19-13}{12}=\frac{6}{12}=\frac{1}{2}\)

a) 16 24 − 1 3 = 16 24 − 8 24 = 24 16 ​ − 3 1 ​ = 24 16 ​ − 24 8 ​ = 8 24 = 1 3 24 8 ​ = 3 1 ​ b) 4 5 − 12 60 = 48 60 − 12 60 = 36 60 = 9 15 5 4 ​ − 60 12 ​ = 60 48 ​ − 60 12 ​ = 60 36 ​ = 15 9 ​ 3. a) 17 6 − 2 6 = 17 − 2 6 = 15 6 6 17 ​ − 6 2 ​ = 6 17−2 ​ = 6 15 ​ b) 16 15 − 11 15 = 16 − 11 15 = 5 15 = 1 3 15 16 ​ − 15 11 ​ = 15 16−11 ​ = 15 5 ​ = 3 1 ​ c) 19 12 − 13 12 = 19 − 13 12 = 6 12 = 1 2 12 19 ​ − 12 13 ​ = 12 19−13 ​ = 12 6 ​ = 2 1 ​