\(\dfrac{3^5}{5^5}\)\(\times x=\dfrac{3^7}{7^7}\)
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SGK Kết nối tri thức với cuộc sống - Trang 111
24 tháng 8 2023 lúc 23:10
Tính bằng cách thuận tiện.
a) \(\dfrac{3}{5}\times\dfrac{7}{11}\times\dfrac{5}{3}\times11\)
b) \(\dfrac{3}{8}\times\dfrac{2}{7}+\dfrac{5}{7}\times\dfrac{3}{8}\)
a)
\(\dfrac{3}{5}\times\dfrac{7}{11}\times\dfrac{5}{3}\times11\\ =\left(\dfrac{3}{5}\times\dfrac{5}{3}\right)\times\left(\dfrac{7}{11}\times11\right)\\ =\dfrac{3\times5}{5\times3}\times\dfrac{7\times11}{11}\\ =1\times7\\ =7\)
b)
\(\dfrac{3}{8}\times\dfrac{2}{7}+\dfrac{5}{7}\times\dfrac{3}{8}\\ =\dfrac{3}{8}\times\left(\dfrac{2}{7}+\dfrac{5}{7}\right)\\ =\dfrac{3}{8}\times\dfrac{7}{7}\\ =\dfrac{3}{8}\times1=\dfrac{3}{8}\)
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21 tháng 5 2022 lúc 16:22
\(\dfrac{-5}{7}\times\dfrac{3}{13}-\dfrac{5}{7}\times\dfrac{10}{13}+1\dfrac{5}{7}\)
Lời giải:
$\frac{-5}{7}\times \frac{3}{13}-\frac{5}{7}\times \frac{10}{13}+1\frac{5}{7}$
$=\frac{5}{7}\times \frac{-3}{13}-\frac{5}{7}\times \frac{10}{13}+1+\frac{5}{7}$
$=\frac{5}{7}\times (\frac{-3}{13}-\frac{10}{13}+1)+1$
$=\frac{5}{7}\times (\frac{-13}{13}+1)+1$
$=\frac{5}{7}\times 0+1=1$
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SGK Kết nối tri thức với cuộc sống - Trang 100
24 tháng 8 2023 lúc 19:38
Tính bằng cách thuận tiện.
a) \(\dfrac{2}{13}\times\dfrac{22}{5}\times\dfrac{13}{2}\) b) \(\dfrac{3}{5}\times\dfrac{6}{7}+\dfrac{6}{7}\times\dfrac{3}{5}\)
\(a,\dfrac{2}{13}\times\dfrac{22}{5}\times\dfrac{13}{2}\\ =\left(\dfrac{2}{13}\times\dfrac{13}{2}\right)\times\dfrac{22}{5}\\ =1\times\dfrac{22}{5}=\dfrac{22}{5}\\ b,\dfrac{3}{5}\times\dfrac{6}{7}+\dfrac{6}{7}\times\dfrac{3}{5}\\ =\dfrac{3}{5}\times\left(\dfrac{6}{7}+\dfrac{6}{7}\right)\\ =\dfrac{3}{5}\times\dfrac{12}{7}=\dfrac{36}{35}\)
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\(a,=\left(\dfrac{2}{13}\times\dfrac{13}{2}\right)\times\dfrac{22}{5}=\dfrac{22}{5}\\ b,=\dfrac{3}{5}\times\left(\dfrac{6}{7}+\dfrac{6}{7}\right)\\ =\dfrac{3}{5}\times\dfrac{12}{7}\\ =\dfrac{36}{35}\)
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SGK Cánh diều - Tập 2 - Trang 74
31 tháng 10 2023 lúc 22:36
Tính:
a) \(\dfrac{5}{2}\times\dfrac{4}{3}+\dfrac{1}{3}\)
b) \(\dfrac{7}{3}-\dfrac{2}{3}:\dfrac{5}{7}\)
c) \(\dfrac{3}{4}\times\left(\dfrac{5}{2}-\dfrac{3}{2}\right)\)
a) $\frac{5}{2} \times \frac{4}{3} + \frac{1}{3} = \frac{{10}}{3} + \frac{1}{3} = \frac{{11}}{3}$
b) $\frac{7}{3} - \frac{2}{3}:\frac{5}{7} = \frac{7}{3} - \frac{2}{3} \times \frac{7}{5} = \frac{7}{3} - \frac{{14}}{{15}} = \frac{{35}}{{15}} - \frac{{14}}{{15}} = \frac{{21}}{{15}} = \frac{7}{5}$
c) $\frac{3}{4} \times \left( {\frac{5}{2} - \frac{3}{2}} \right) = \frac{3}{4} \times 1 = \frac{3}{4}$
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C=\(\dfrac{7}{19}\times\dfrac{5}{8}\times\dfrac{-19}{7}\)
D=\(\dfrac{3}{7}\times\dfrac{9}{11}+\dfrac{3}{7}\times\dfrac{2}{11}\)
C)
`7/19xx5/8xx (-19)/7`
`=7/19xx (-19/7)xx5/8`
`= -1xx5/8`
`=-5/8`
D)
`3/7xx9/11+3/7xx2/11`
`=3/7xx(9/11+2/11)`
`=3/7xx11/11`
`=3/7xx1`
`=3/7`
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8 tháng 5 2022 lúc 13:25
\(\dfrac{3}{7}\times\dfrac{5}{8}+\dfrac{3}{7}\times\dfrac{11}{8}-\dfrac{-1}{7}\)
31 tháng 12 2022 lúc 19:46
a) dfrac{-2}{15}times xdfrac{-2}{7} b) dfrac{7}{-5}times x-3 c) -dfrac{4}{9}xdfrac{1}{2} d) dfrac{8}{3}div xdfrac{-3}{8} e) xdivdfrac{3}{-4}-12 f) left(-1right)div xdfrac{-3}{7}+dfrac{4}{5} g)dfrac{4}{11}x-dfrac{1}{3}dfrac{2}{5} i) dfrac{-6}{7}-dfrac{1}{5}x-4j) dfrac{1}{2}+dfrac{2}{3}div7dfrac{-1}{3} k) dfrac{-5}{2}+xdiv7dfr...
Đọc tiếp
a) \(\dfrac{-2}{15}\times x=\dfrac{-2}{7}\) b) \(\dfrac{7}{-5}\times x=-3\) c) \(-\dfrac{4}{9}x=\dfrac{1}{2}\) d) \(\dfrac{8}{3}\div x=\dfrac{-3}{8}\)
e) \(x\div\dfrac{3}{-4}=-12\) f) \(\left(-1\right)\div x=\dfrac{-3}{7}+\dfrac{4}{5}\) g)\(\dfrac{4}{11}x-\dfrac{1}{3}=\dfrac{2}{5}\) i) \(\dfrac{-6}{7}-\dfrac{1}{5}x=-4\)
j) \(\dfrac{1}{2}+\dfrac{2}{3}\div7=\dfrac{-1}{3}\) k) \(\dfrac{-5}{2}+x\div7=\dfrac{-1}{3}\) L) \(\dfrac{-3}{2}-\dfrac{1}{4}\div x=-1\)
a: =>x*2/15=2/7
=>x=2/7:2/15=2/7*15/2=15/7
b: x=3:7/5=15/7
c: x=-1/2:4/9=-1/2*9/4=-9/8
d: x=-8/3:3/8=-64/9
g: =>4/11x=2/5+1/3=6/15+5/15=11/15
=>x=11/15:4/11=121/60
l: =>1/4:x=1-3/2=-1/2
=>x=-1/4:1/2=-1/4*2=-1/2
k: =>x:7=-1/3+5/2=-2/6+15/6=13/6
=>x=91/6
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17 tháng 2 2023 lúc 22:48
\(\dfrac{3}{8}\times\dfrac{-5}{7}+\left(\dfrac{-5}{7}\right)\times\dfrac{5}{8}\)
giúp mk với 
`3/8 xx (-5)/7 + (-5/7) xx 5/8`
`= -5/7 xx (3/8+5/8)`
`=-5/7 xx 8/8`
`=-5/7 xx 1`
`=-5/7`
có vẻ hơi sai lớp vs môn nhỉ:<
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\(\dfrac{3}{8}.\dfrac{-5}{7}+\left(\dfrac{-5}{7}\right).\dfrac{5}{8}=\dfrac{-5}{7}.\left(\dfrac{3}{8}+\dfrac{5}{8}\right)=\dfrac{-5}{7}.1=\dfrac{-5}{7}\)
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38 ×−57+(−57)×5838 ×-57+(-57)×58
=−57×(38+58)=-57×(38+58)
=−57×88=-57×88
=−57×1=-57×1
=−57
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\(\dfrac{7}{12}\times\dfrac{2}{3}-\dfrac{5}{3}\times\dfrac{7}{12}+\dfrac{7}{12}\times3\)
