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3/5 - 1/3 x (2,48 + 0,52) x y : 60 : 5 = 1/5
1/3 x (2,48+0,52) x y : 60 : 5 = 2/5
1/3 x 3 x y : 60 : 5 = 2/5
y: 60 : 5 =2/5
y: 60 =2/5 x 5
y : 60 =2
y = 2 x 60
y =120
Ta có: \(\dfrac{3}{5}-\dfrac{1}{3}\left(2.48+0.52\right)\cdot y:60:5=\dfrac{1}{5}\)
\(\Leftrightarrow\dfrac{3}{5}-\dfrac{1}{3}\cdot3\cdot y\cdot\dfrac{1}{60}\cdot\dfrac{1}{5}=\dfrac{1}{5}\)
\(\Leftrightarrow y\cdot\dfrac{1}{300}=\dfrac{2}{5}\)
hay y=120
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ta có \(\frac{x}{3}=\frac{y}{8}=\frac{z}{5}\)
=> \(\frac{3x}{9}=\frac{y}{8}=\frac{z}{5}=\frac{3x+y-z}{9+8-5}=\frac{14}{12}=\frac{7}{6}\)
=> \(\frac{x}{3}=\frac{y}{8}=\frac{z}{5}\)\(=\frac{7}{6}\)
=> \(x\)\(=\frac{7\cdot3}{6}=\frac{21}{6}=\frac{7}{2}\)
=> \(y=\frac{7\cdot8}{6}=\frac{56}{6}\)
=>\(z=\frac{7\cdot5}{6}=\frac{35}{6}\)
số xấu vậy em
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Sửa đề: y+y:0,5+y:0,2+y:0,1=5
=>y+2y+5y+10y=5
=>18y=5
=>y=5/18
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a: =>y+1,2=(5,34-10,34):5=-1
=>y=-2,2
b: =>x(x+1)/2=111a
=>x(x+1)=222a
=>\(x\in\varnothing\)
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(y+1)+(y+2)+(y+3)+.....+(y+100)=6050
y+1+y+2+y+3+.......+y+100=6050
y+y+y+......+1+2+3+4+5+.....+100=6050
100 nhân 7+1+2+3+4+5+......+100=6050 (1)
Tính 1+2+3+4+......+100
có 100+1=101
99+2=101
98+3=101
...........
50+51=101
Mà ta có tất cả 50 cặp bằng 101
nên 1+2+3+4+5+6+....+100=101 nhân 50+=5050 (2)
Thế (2) vào (1) ta có 100 nhân y+5050=6050
100 nhân y =6050-5050
100 nhân y =1000
y =1000:100
y =10
(y + 1) + (y+2) + (y+3) + .... + (y+100) = 6050
100 * y + (1+2+3+4+....+100) = 6050
100*y = 6050 - 5050 = 1000
y = 1000 / 100 = 10
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\(\hept{\begin{cases}\frac{x}{3}+\frac{y}{5}=12\\\frac{x}{5}+\frac{y}{7}=8\end{cases}\Rightarrow\hept{\begin{cases}\frac{x}{15}+\frac{y}{25}=\frac{12}{5}\\\frac{x}{15}+\frac{y}{21}=\frac{8}{3}\end{cases}}}\)
\(\Rightarrow\left(\frac{x}{15}+\frac{y}{21}\right)-\left(\frac{x}{15}+\frac{y}{25}\right)=\frac{12}{5}-\frac{8}{3}\)
\(\Rightarrow\frac{y}{21}-\frac{y}{25}=\frac{-4}{15}\)
\(\Rightarrow\frac{4y}{525}=-\frac{4}{15}\Rightarrow\frac{4y}{525}=\frac{-140}{525}\)
\(\Rightarrow y=-35\Rightarrow x=65\)