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\(y\times\dfrac{1}{2}+y\times\dfrac{1}{6}+y\times\dfrac{1}{12}+y\times\dfrac{1}{20}=\dfrac{8}{5}\)
\(y\times\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}\right)=\dfrac{8}{5}\)
\(y\times\dfrac{4}{5}=\dfrac{8}{5}\)
\(\dfrac{8}{5}:\dfrac{4}{5}\)
\(y=\dfrac{8}{4}=2\)
`1716:y=12xx13`
`1716:y=156`
`y=1716:156`
`y=11`
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`y xx 2/3+y xx 1/6=10/3`
`y xx(2/3+1/6)=10/3`
`y xx(4/6+1/6)=10/3`
`y xx5/6=10/3`
`y=10/3:5/6`
`y=10/3xx6/5=4`
1716 : y = 12 \(\times\) 13
1716 : y = 156
y = 1716 : 156
y = 11
\(y\times\dfrac{2}{3}+y\times\dfrac{1}{6}=\dfrac{10}{3}\)
\(y\times\left(\dfrac{2}{3}+\dfrac{1}{6}\right)=\dfrac{10}{3}\)
\(y\times\dfrac{5}{6}=\dfrac{10}{3}\)
\(y=\dfrac{10}{3}:\dfrac{5}{6}\)
\(y=4\)
a,+) 4/x=12/15
=>15*4=12*x
=>60=12*x
=>x=5;có 4/x=y/45
=>4/5=y/45
=>36/45=y/45
=>y=36
Vậy x=5:y=36
b,3/x=1/y=6/24
=>3/x=1/y=1/4
có: 1/y=1/4
=>y=4
có: 1/4=3/x
=>1x=3*4
=>x=12
Vây x=12
y=4
hok tot
a) \(\frac{4}{5}=\frac{12}{15}=\frac{36}{45}\)
Tự giải quyết nốt =))
=>( y - 1/2 )+( y - 1/6 )+...+( y- 1/90 ) = 1
=>y + y+.. + y - 1/2 - 1/6-...- 1/90 = 1
=>y + y+..+ y - 1/(1x2) - 1/(2x3) - 1/(3x4)-...- 1/(9x10) = 1
=> 9y -( 2-1)/(1x2) - (3-2)/(2x3)-...- (10-9)/(9x10) = 1
=>9y- 2/(1x2) + 1(1x2) - 3/(2x3) + 2/(2x3)-...- 10/(9x10) + 9(9x10) = 1
=> 9y- 1 + 1/2 - 1/2 + 1/3-...- 1/9 + 1/10 = 1
=>9y- 1 + 1/10 = 1
=> 9y- 9/10 =1
=>y=19/90
Vậy y=19/90
y=19/10