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Lời giải:
$4,5\times 5,4< y\times 2< 5,5\times 5,4$
$24,3< y\times 2< 29,7$
Vì $y\times 2$ là số chẵn nên $y\times 2=26$ hoặc $y\times 2=28$
Suy ra $y=13$ hoặc $y=14$.
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4,5x5,4=24,3
5,5x5,4=29,7
Yx2 có thể là:25,26
Y có thể là:12,5;13
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\(y\cdot15,5-y\cdot5,5,=120\)
\(y\cdot(15,5-5,5)=120\)
\(y\cdot10=120\)
\(y=120\div10\)
\(y=12\)
y * 15,5 - y * 5,5 =120
y * [15,5 -5,5] =120
y * 10 = 120
y= 120 : 10
y = 12
hok tốt nha
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\(4,5\times20,1+5,5\times28,9+4,5\times3,3-5,5\times5,5\)
\(=\left(4,5\times20,1+4,5\times3,3\right)+\left(5,5\times28,9-5,5\times5,5\right)\)
\(=4,5\times\left(20,1+3,3\right)+5,5\times\left(28,9-5,5\right)\)
\(=4,5\times23,4+5,5\times23,4\)
\(=23,4\times\left(4,5+5,5\right)\)
\(=23,4\times10=234\)
4,5 x 20,1 + 5,5 x 28,9 + 4,5 x 3,3 - 5,5 x 5,5
= 4,5 x ( 20,1 + 3,3 ) + 5,5 x ( 28,9 - 5,5 )
= 4,5 x 23,4 + 5,5 x 23,4
= ( 4,5 + 5,5 ) x 23,4
= 10 x 23,4
= 234
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a) y x 3,9 + y x 0,1 = 2,7
y x ( 3,9 + 0,1 ) = 2,7
y = 2,7 : 4
y = 0,675
b) 12, 3 : y - 4,5 : y = 15
( 12,3 - 4,5 ) : y =15
7,8 : y = 15
y = 7,8 : 15
y = 0,52
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a; 100% : \(x\) - 50% : \(x\) + 40% : \(x\) = 18 + 30% : \(x\)
(100% - 50% + 40%): \(x\) = 18 + 30% : \(x\)
90% : \(x\) = 18 + 30% : \(x\)
90%: \(x\) - 30%: \(x\) = 18
60% : \(x\) = 18
\(x\) = 60% : 18
\(x\) = \(\dfrac{1}{30}\)
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Bài làm
3 x ( y + y + y ) = 4,5
=> 3 x 3y = 4,5
=> 3y = 4,5 : 3
=> 3y = 1,5
=> y = 1,5 : 3
=> y = 0,5
Vậy y = 0,5
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\(y\times5,5+y\times4,5=150\)
\(y\times\left(5,5+4,5\right)=150\)
\(y\times10=150\)
\(y=150\div10\)
\(y=15\)
y * 5,5 + y * 4,5 = 150
y * (5,5 + 4,5) = 150
y * 10 = 150
y = 150 : 10
y = 15