45/15 - (1/2+(1/3+(1/4)^-1)^-1)^-1
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`4/7+4`
`=4/7+4/1`
`=4/7+28/7`
`=32/7`
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`3+6/11`
`=33/11+6/11`
`=39/11`
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`3-5/7`
`=3/1-5/7`
`=21/7-5/7`
`=16/7`
__
`21/9-2`
`=21/9-18/9`
`=3/9`
`=1/3`
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`15/24+2`
`=15/24+48/24`
`=63/24`
`=21/16`
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`63/45-20/25`
`=63/45-4/5`
`=63/45-36/45`
`=27/45`
`=9/15`
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`3/4-2/8`
`=3/4-1/4`
`=2/4`
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`6/7-5/8`
`=48/56-35/56`
`=13/56`
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`37/45-5/9`
`=37/45-25/45`
`=12/45`
`=4/15`
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`46/39-11/13`
`=46/39-33/39`
`=13/39`
`=1/2`
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`5/12+3/4+1/3`
`=5/12+9/12+4/12`
`=14/12+4/12`
`=18/12`
`=3/2`
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`1/2+3/7+11/14`
`=7/14+6/14+11/14`
`=13/14+11/14`
`=24/14`
`=12/7`
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`7/10-(1/5+1/4)`
`=7/10-(4/20+5/20)`
`=7/10-9/20`
`=14/20-9/20`
`=5/20`
`=1/4`
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`15/4-2/3-3/4`
`=(15/4-3/4)-2/3`
`=12/4-2/3`
`=3-2/3`
`=9/3-2/3`
`=7/3`
bn ơi bài này ko có 1/4 đâu:
đặt A=\(\frac{1}{2}+\frac{1}{3}+\frac{1}{6}+...+\frac{1}{36}+\)\(\frac{1}{45}\)
\(\frac{1}{2}A\)=> \(\frac{1}{2}A\)= \(\frac{1}{4}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{72}+\frac{1}{90}\)
\(\frac{1}{2}A\)= \(\frac{1}{4}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{8\cdot9}+\frac{1}{9\cdot10}\)
\(\frac{1}{2}A\)= \(\frac{1}{4}\)+ \(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-...+\frac{1}{9}-\frac{1}{10}\)
\(\frac{1}{2}A\)= \(\frac{1}{4}+\frac{1}{2}-\frac{1}{10}=\frac{5}{20}+\frac{10}{20}-\frac{2}{20}=\frac{13}{20}\)
=> A = \(\frac{13}{20}:\frac{1}{2}=\frac{13}{10}\)
Chúc bn học tốt !
a: \(-\dfrac{4}{7}-\dfrac{5}{13}\cdot\dfrac{-39}{25}+\dfrac{-1}{42}:\dfrac{-5}{6}\)
\(=\dfrac{-4}{7}+\dfrac{3}{5}+\dfrac{1}{35}\)
\(=\dfrac{-20}{35}+\dfrac{21}{35}+\dfrac{1}{35}\)
\(=\dfrac{2}{35}\)
\(45\times1+45\times2+45\times3+45\times4+45\times5+45\times15+45\times20+45\times50\)
\(=45\times\left(1+2+3+4+5+15+20+50\right)\)
\(=45\times100\)
\(=4500\)
kết quả bằng : 4500 chac chan minh tinh bang may tinh ma
chúc bạn học giỏi
\(\dfrac{45}{15}-\left\{\dfrac{1}{2}+\left[\dfrac{1}{3}+\left(\dfrac{1}{4}\right)^{-1}\right]^{-1}\right\}^{-1}\)
\(=3-\left[\dfrac{1}{2}+\left(\dfrac{1}{3}+4\right)^{-1}\right]^{-1}\\ =3-\left(\dfrac{1}{2}+\dfrac{3}{13}\right)^{-1}\\ =3-\left(\dfrac{19}{26}\right)^{-1}\\ =3-\dfrac{26}{19}\\ =\dfrac{31}{19}\)
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