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\(\dfrac{7}{2}+\dfrac{2}{25}=\dfrac{7\times25}{2\times25}+\dfrac{2\times2}{25\times2}=\dfrac{175}{50}+\dfrac{4}{50}=\dfrac{179}{50}\)
\(\dfrac{23}{5}-\dfrac{11}{3}=\dfrac{23\times3}{5\times3}-\dfrac{11\times5}{3\times5}=\dfrac{69}{15}-\dfrac{55}{15}=\dfrac{14}{15}\)
\(\dfrac{3}{7}-\dfrac{1}{14}=\dfrac{3\times2}{7\times2}-\dfrac{1}{14}=\dfrac{6}{14}-\dfrac{1}{14}=\dfrac{5}{14}\)
\(\dfrac{8}{5}:\dfrac{1}{3}=\dfrac{8}{5}\times3=\dfrac{8\times3}{5}=\dfrac{24}{5}\)
\(2:\dfrac{5}{3}=2\times\dfrac{3}{5}=\dfrac{2\times3}{5}=\dfrac{6}{5}\)
\(\dfrac{4}{5}\times\dfrac{7}{15}=\dfrac{4\times7}{5\times15}=\dfrac{28}{75}\)
Lời giải:
\(\frac{7}{2}+\frac{2}{25}=\frac{7\times 25+2\times 2}{2\times 25}=\frac{179}{50}\)
\(\frac{23}{5}-\frac{11}{3}=\frac{23\times 3-5\times 11}{5\times 3}=\frac{14}{15}\)
\(\frac{3}{7}-\frac{1}{14}=\frac{6}{14}-\frac{1}{14}=\frac{6-1}{14}=\frac{5}{14}\)
\(\frac{8}{5}: \frac{1}{3}=\frac{8}{5}\times 3=\frac{24}{5}\)
$2: \frac{5}{3}=\frac{2\times 3}{5}=\frac{6}{5}$
$\frac{4}{5}\times \frac{7}{15}=\frac{28}{75}$
\(\frac{5}{7}.\frac{12}{11}+\frac{9}{7}.\frac{2}{11}-\frac{5}{7}.\frac{14}{11}\)
\(=\frac{1}{7}.\frac{1}{11}.\left(5.12+9.2-5.14\right)\)
\(=\frac{1}{77}.\left(60+18-70\right)\)
\(=\frac{1}{77}.8=\frac{8}{77}\)
\(\left(\frac{5}{7}-x\right)\times\frac{14}{5}=\frac{7}{10}+\frac{1}{2}\)
\(\left(\frac{5}{7}-x\right)\times\frac{14}{5}=\frac{6}{5}\)
\(\frac{5}{7}-x=\frac{6}{5}:\frac{14}{5}\)
\(\frac{5}{7}-x=\frac{3}{7}\)
\(x=\frac{5}{7}-\frac{3}{7}\)
\(x=\frac{2}{7}\)
x=2/7
bài này lớp 4
mình đã học rồi
cho lên bay giờ mình quen rùi
( 5/7 - y ) * 14/5 = 7/10 + 1/2
( 5/7 - y ) x 14/5 = 6/5
5/7 - y = 6/5 : 14/5
5/7 - y = 3/7
y = 5/7 - 3/7
y = 2/7
a) 8/15 + 1 = 23/15
b) 3/14 + 11/14 - 2/3 = 1- 2/3 = 1/3
c) 7/15 * (5/3+2/3) = 7/15 * 7/3= 49/45
d) 6/11 + 5/11 - 3/5 = 1 - 3/5 = 2/5
6 + 2 + 5 + 7 + 5 =
= 6 + 2 + 7 + ( 5 + 5 )
=8 + 7 + 10
=15 + 10
= 25
`5/7xx5/11+5/7xx2/11-5/7xx14/11`
`=5/7xx(5/11+2/11-14/11)`
`=5/7xx(-7/11)`
`=-5/11`
\(\left(\frac{5}{7}-y\right)\cdot\frac{14}{5}=\frac{7}{10}+\frac{1}{2}=\left(\frac{5}{7}-y\right)\cdot\frac{14}{5}=\left(\frac{5}{7}-y\right)\cdot\frac{14}{5}=\frac{6}{5}\)\(\frac{6}{5}\)
\(=>\frac{5}{7}-y=\frac{6}{5}\) / \(\frac{14}{5}=\frac{5}{7}-y=\frac{3}{7}=\frac{5}{7}-\frac{3}{7}=\frac{2}{7}\)
\(=>y=\frac{2}{7}\)
\(\dfrac{14}{5}\div\dfrac{7}{2}=\dfrac{14}{5}\times\dfrac{2}{7}=\dfrac{28}{35}=\dfrac{4}{5}\)
= \(\dfrac{4}{5}\)