Tính bằng hai cách : 1 3 - 1 5 × 1 2
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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
`(1/3 + 1/5) xx 1/4`
`= ( 5/15 + 3/15) xx 1/4`
`= 8/15 xx 1/4`
`= 8/60`
`= 2/15`
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`(1/3 + 1/5) xx 1/4`
`= 1/3 xx 1/4 + 1/5 xx 1/4`
`= 1/12 +1/20`
`=2/15`
\(C_1:\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{4}\times\dfrac{1}{3}+\dfrac{1}{4}\times\dfrac{1}{5}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{2}{15}\)
\(C_2:\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8\times1}{15\times4}=\dfrac{8}{60}=\dfrac{2}{15}\)
Cách 1 : ( 7/5 x2 ) + ( 4/3 x 2 )
= 14/5 + 8/3
= 82/15
Cách 2 : ( 7/5 +4/3) x 2
= 41/15 x 2
= 82/15
a) \(\left(\frac{1}{3}+\frac{1}{5}\right)\cdot\frac{1}{2}\) b)\(\left(\frac{1}{3}-\frac{1}{5}\right)\cdot\frac{3}{5}\)
\(=\frac{8}{15}\cdot\frac{1}{2}\) \(=\frac{2}{15}\cdot\frac{3}{5}\)
\(=\frac{4}{15}\) \(=\frac{2}{25}\)
\(a,\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{8}{15}\times\dfrac{1}{4}=\dfrac{8}{60}=\dfrac{2}{15}\)
\(\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\times\dfrac{1}{4}=\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{5}\times\dfrac{1}{4}=\dfrac{1}{12}+\dfrac{1}{20}=\dfrac{20}{240}+\dfrac{12}{240}=\dfrac{32}{240}=\dfrac{2}{15}\)
\(b,\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}=\dfrac{2}{5}\times\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\times1=\dfrac{2}{5}\)
\(\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}=\dfrac{6}{35}+\dfrac{8}{35}=\dfrac{14}{35}=\dfrac{2}{5}\)
trả lời nhanh nha! trả lời trong tối hôm nay 19/3/2023 ạ
Cách 1:
\(\left(\frac{1}{3}-\frac{1}{5}\right).\frac{1}{2}\)
\(=\left(\frac{5}{15}-\frac{3}{15}\right).\frac{1}{2}\)
\(=\frac{2}{15}.\frac{1}{2}\)
\(=\frac{1}{15}\)
Cách 2:
\(\left(\frac{1}{3}-\frac{1}{5}\right).\frac{1}{2}\)
\(=\frac{1}{3}.\frac{1}{2}-\frac{1}{5}.\frac{1}{2}\)
\(=\frac{1}{6}-\frac{1}{10}\)
\(=\frac{10}{60}-\frac{6}{60}\)
\(=\frac{1}{15}\)
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: =17/21(3/5+2/5)=17/21
1 3 - 1 5 × 1 2 = 5 15 - 3 15 × 1 2 = 2 15 × 1 2 = 2 30 = 1 15 1 3 - 1 5 × 1 2 = 1 3 × 1 2 - 1 5 × 1 2 = 1 6 - 1 10 = 10 60 - 6 60 = 4 60 = 1 15