a) Cách 1 : (3/4 + 1/2) x 5/7

               = 5/4 x 5/7

                = 25/28

Cách 2 : (3/4 + 1/2) x 5/7

           = 3/4 x 5/7 + 1/2 x 5/7

            = 15/28 + 5/14

            = 25/28

b) Cách 1 : 5/7 x 13/21 + 2/7 x 13/21

= 65/147 + 26/147

= 13/21

Cách 2 : 5/7 x 13/21 + 2/7 x 13/21

= (5/7 + 2/7) x 13/21

= 1 x 13/21

= 13/21

câu c tự làm

8 /15 :2/3+7/15:2/3 =                                              tính bằng 2 cách nhé các bạn

`(1/3 + 1/5) xx 1/4`

`= ( 5/15 + 3/15) xx 1/4`

`= 8/15 xx 1/4`

`= 8/60`

`= 2/15`

__

`(1/3 + 1/5) xx 1/4`

`= 1/3 xx 1/4 + 1/5 xx 1/4`

`= 1/12 +1/20`

`=2/15`

\(C_1:\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{4}\times\dfrac{1}{3}+\dfrac{1}{4}\times\dfrac{1}{5}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{2}{15}\)

\(C_2:\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8\times1}{15\times4}=\dfrac{8}{60}=\dfrac{2}{15}\)

a: Cách 1:

\(\left(\frac13+\frac15\right)\times\frac12\)

\(=\left(\frac{5}{15}+\frac{3}{15}\right)\times\frac12\)

\(=\frac{8}{15}\times\frac12=\frac{8}{30}=\frac{4}{15}\)

Cách 2: \(\left(\frac13+\frac15\right)\times\frac12\)

\(=\frac13\times\frac12+\frac15\times\frac12\)

\(=\frac16+\frac{1}{10}=\frac{5}{30}+\frac{3}{30}=\frac{8}{30}=\frac{4}{15}\)

b: Cách 1: \(\left(\frac13-\frac15\right)\times\frac12\)

\(=\frac{5-3}{15}\times\frac12\)

\(=\frac{2}{15}\times\frac12=\frac{1}{15}\)

Cách 2: \(\left(\frac13-\frac15\right)\times\frac12\)

\(=\frac13\times\frac12-\frac15\times\frac12\)

\(=\frac16-\frac{1}{10}\)

\(=\frac{5}{30}-\frac{3}{30}=\frac{2}{30}=\frac{1}{15}\)

\(a,\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8}{60}=\dfrac{2}{15}\)

\(\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{5}\times\dfrac{1}{4}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{20}{240}+\dfrac{12}{240}=\dfrac{32}{240}=\dfrac{2}{15}\)

\(b,\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}=\dfrac{2}{5}\times\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\times1=\dfrac{2}{5}\)

\(\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}=\dfrac{6}{35}+\dfrac{8}{35}=\dfrac{14}{35}=\dfrac{2}{5}\)

trả lời nhanh nha! trả lời trong tối hôm nay 19/3/2023 ạ

a: Cách 1: \(\left(\frac23\times\frac45\right)\times\frac56\)

\(=\frac{2\times4}{3\times5}\times\frac56\)

\(=\frac{8}{15}\times\frac56=\frac{40}{90}=\frac49\)

Cách 2:

\(\left(\frac23\times\frac45\right)\times\frac56\)

\(=\frac23\times\frac45\times\frac56\)

\(=\frac23\times\frac46=\frac23\times\frac23=\frac49\)

b: Cách 1:

\(\left(\frac12+\frac13\right)\times\frac15\)

\(=\frac{3+2}{6}\times\frac15\)

\(=\frac56\times\frac15\)

\(=\frac16\)

Cách 2:

\(\left(\frac12+\frac13\right)\times\frac15\)

\(=\frac12\times\frac15+\frac13\times\frac15\)

\(=\frac{1}{10}+\frac{1}{15}=\frac{3}{30}+\frac{2}{30}=\frac{5}{30}=\frac16\)

nhanh lên

a: \(=\dfrac{3}{22}\cdot22\cdot\dfrac{3}{11}=3\cdot\dfrac{3}{11}=\dfrac{9}{11}\)

b: \(=\dfrac{5}{6}\cdot\dfrac{2}{5}=\dfrac{1}{3}\)

c: \(=\dfrac{17}{21}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{17}{21}\)

\(=\dfrac{14+15}{18}\cdot\dfrac{3}{5}=\dfrac{29}{18}\cdot\dfrac{3}{5}=\dfrac{29}{30}\)

Bài 1:

a: Cách 1: \(\left(\frac23-\frac45\right)\times25\)

\(=\left(\frac{10}{15}-\frac{12}{25}\right)\times25\)

\(=-\frac{2}{25}\times15=-\frac{30}{15}=-\frac65\)

Cách 2: \(\left(\frac23-\frac45\right)\times25\)

\(=\frac23\times25-\frac45\times25\)

\(=\frac{50}{3}-20=\frac{50}{3}-\frac{100}{5}=\frac{50}{3}-20=\frac{50}{3}-\frac{60}{3}=-\frac{10}{3}\)

b: Sửa đề: \(\frac34\times\frac25+\frac34\times\frac27\)

Cách 1: \(\frac34\times\frac25+\frac34\times\frac27\)

\(=\frac34\times\left(\frac25+\frac27\right)\)

\(=\frac34\times\left(\frac{14}{35}+\frac{10}{35}\right)\)

\(=\frac34\times\frac{24}{35}=\frac{72}{140}=\frac{18}{35}\)

Cách 2:

\(\frac34\times\frac25+\frac34\times\frac27\)

\(=\frac{6}{20}+\frac{6}{28}\)

\(=\frac{42}{140}+\frac{30}{140}=\frac{72}{140}=\frac{18}{35}\)

Bài 2:

a: \(x:\frac25=\frac23\)

=>\(x=\frac23\times\frac25=\frac{4}{15}\)

b: \(x:\frac23=\frac49\)

=>\(x=\frac49\times\frac23=\frac{8}{27}\)

a) Cách 1

\(\frac{3}{4}\)x \(\frac{1}{2}\)x \(2\)

= \(\frac{3}{8}\)x \(2\)

= \(\frac{3}{4}\)

Cách 2

\(\frac{3}{4}\)x \(\frac{1}{2}\)x \(2\)

= \(\frac{3}{4}\)x \(\left(\frac{1}{2}x2\right)\)

= \(\frac{3}{4}\)x 1

= \(\frac{3}{4}\)

1/4*1/2+1/6*1/2=1/8+1/12=20/96                                  C2     ( 1/4+1/6)*1/2

                                                                                             =10/24*1/2=10/48

b,(3/2-2/5)*1/3=11/10*1/3                                                 C2    3/2*1/3+2/5*1/3

                                                                                                  =3/6+2/15=     53/90

=11/30

\(\left(\frac{1}{4}+\frac{1}{6}\right)x\frac{1}{2}\)                                                           \(\left(\frac{3}{2}-\frac{2}{5}\right)x\frac{1}{3}\)

\(c1:=\frac{5}{12}x\frac{1}{2}=\frac{5}{24}\)                                                   \(c1:\frac{11}{10}x\frac{1}{3}=\frac{11}{30}\)

\(c2:=\frac{1}{4}x\frac{1}{2}+\frac{1}{6}x\frac{1}{2}\)                                              \(c2:\frac{3}{2}x\frac{1}{3}-\frac{2}{5}x\frac{1}{3}\)

\(=\frac{1}{8}+\frac{1}{12}=\frac{12}{96}+\frac{8}{96}=\frac{20}{96}=\frac{5}{24}\)                         \(=\frac{1}{2}-\frac{2}{15}=\frac{11}{30}\)

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