\(\dfrac{15}{16}\cdot\dfrac{8}{3}\cdot\dfrac{3}{4}=\dfrac{15\cdot8\cdot3}{8\cdot2\cdot3\cdot4}=\dfrac{15}{2\cdot4}=\dfrac{15}{16}\)

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Giải chi tiết cho mình nha

\(\dfrac{2}{5}+\dfrac{11}{15}=\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)

\(\dfrac{7}{8}-\dfrac{7}{9}=\dfrac{63}{72}-\dfrac{56}{72}=\dfrac{7}{72}\)

\(\dfrac{11}{13}\times\dfrac{26}{31}=\dfrac{22}{31}\)

\(\dfrac{16}{24}:4=\dfrac{16}{24}\times\dfrac{1}{4}=\dfrac{4}{24}=\dfrac{1}{6}\)

\(30:\dfrac{6}{5}=30\times\dfrac{5}{6}=25\)

\(\dfrac{9}{16}:4=\dfrac{9}{16}\times\dfrac{1}{4}=\dfrac{9}{64}\)

\(\dfrac{1}{2}:\dfrac{1}{3}\times\dfrac{8}{15}=\dfrac{1}{2}\times3\times\dfrac{8}{15}=\dfrac{4}{5}\)

2/5 + 11/15 = 17/15
7/8 - 7/9 = 7/72
11/13 x 26/31 = 22/31
16/24 : 4 = 1/6
30 : 6/5 = 25
9/16 : 4 = 9/64
1/2 : 1/3 x 8/15 = 3/2 x 8/15 = 4/5

=2x2/1x3 x 3x3/2x4x4/3x5 x ... x 11x11/10x12

=2x2x3x3x4x4x...x11x11/1x3x2x4x3x5x...x10x12

= 2x3x4x...x11)x(2x3x4x...x11)/(1x2x3x4x...x11)/(1x2x3x...x10)x(2x3x4x...x11)

=11x2/1x12

=22/12

=11/6

4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x\(\dfrac{4^2}{3\cdot5}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)

4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)

12 mình chịu

11/15 + 8/5=                   Tính phân số

6/7 - 5/21=

25/4 x 16/100

7 x 2/49 =

4/3 : 2/9

5/8 : 25 =

đây là kết quả của mình nhé .

\(x=\dfrac{3}{4}+\dfrac{8}{9}+\dfrac{15}{16}+...+\dfrac{99}{100}=\dfrac{1.3}{2^2}+\dfrac{2.4}{3^2}+\dfrac{3.5}{4^2}+...+\dfrac{9.11}{10^2}=\dfrac{1.2.3...9}{2.3.4...10}.\dfrac{3.4.5...11}{2.3.4...10}=\dfrac{1}{10}.\dfrac{11}{2}=\dfrac{11}{20}\)

a)    \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)

\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)

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

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

b)   \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)

\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)

\(=1\times\frac{1}{2}=\frac{1}{2}\)

c)   \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)

\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)

\(=\frac{247}{420}+\frac{72}{420}\)

\(=\frac{319}{420}\)

còn phần D đâu bn 

tích cho chị nha

 câu a)     = 5/6

 câu b = 1/2

 câu c = 319/420

a,\(\frac{4}{3}\)x \(\frac{9}{8}\)x \(\frac{16}{15}\)x \(\frac{25}{24}\)

= \(\frac{5}{3}\)

b, \(\frac{4}{3}\)x \(\frac{9}{8}\)x \(\frac{16}{15}\)x \(\frac{25}{24}\)x \(\frac{36}{35}\)x \(\frac{49}{48}\)x \(\frac{64}{63}\)x \(\frac{81}{80}\)

= \(\frac{9}{5}\)

chi tiết hơn đc k bn

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