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\(x+x\cdot3:\dfrac{2}{9}+x:\dfrac{2}{7}=252\)
\(\Leftrightarrow x+x\cdot3\cdot\dfrac{9}{2}+x\cdot\dfrac{7}{2}=252\)
\(\Leftrightarrow x\cdot18=252\)
hay x=14
![](https://rs.olm.vn/images/avt/0.png?1311)
Đặt A = 1/2+1/4+1/8+1/18+1/32+1/64+1/128+1/256
=> 2A = 1+1/2+1/4+1/8+1/18+1/32+1/64+1/128
=> 2A - A = 1 - 1/256
=> A = 255/256 nhé!
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\(7-y:2=3\)
\(y:2=7-3\)
\(y:2=4\)
\(y=4.2\)
\(y=8\)
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y : 0,25 + y : 0,125 - y : 0,5 = 2,63
y : ( 0,25 + 0,125 - 0,5 ) = 2,63
y : ( 0,375 - 0,5 ) = 2,63
y : ( -0,125) = 2,63
y = 2,63 x ( -0,125 )
y = -0,32875
y:0,25+y:0,125-y:0,5=2,63
y:1/4+y:1/8-y:1/2=2,63
y x 4 +y x 8 - y x 2=2,63
y x (4+8-2)=2,63
y x 10=2,63
y=2,63 : 10
y=0,263
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\(\frac{5}{7}+y\times\frac{1}{2}=\frac{8}{7}:\frac{3}{2}\)
=> \(\frac{5}{7}+y\times\frac{1}{2}=\frac{8}{7}\times\frac{2}{3}\)
=> \(\frac{5}{7}+y\times\frac{1}{2}=\frac{16}{21}\)
=> \(y\times\frac{1}{2}=\frac{16}{21}-\frac{5}{7}=\frac{1}{21}\)
=> \(y=\frac{1}{21}:\frac{1}{2}=\frac{1}{21}\cdot2=\frac{2}{21}\)
5/7 + Y x 1/2 = 8/7 : 3/2
=> 5/7 + Y x 1/2 = 16/21
=> Y x 1/2 = 16/21 - 5/7
=> Y x 1/2 = 1/21
=> Y = 1/21 : 1/2
=> Y = 2/21
Hok tốt ^^
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c)\(\dfrac{3}{8}\times\dfrac{5}{8}+y=\dfrac{5}{4}\)
\(\dfrac{15}{64}+y=\dfrac{5}{4}\)
\(y=\dfrac{5}{4}-\dfrac{15}{64}\)
\(y=\dfrac{65}{64}\)
d, \(\dfrac{3}{8}+\dfrac{5}{8}\times y=\dfrac{5}{4}\)
\(\dfrac{5}{8}\times y=\dfrac{5}{4}-\dfrac{3}{8}\)
\(\dfrac{5}{8}\times y=\dfrac{7}{8}\)
\(y=\dfrac{7}{8}:\dfrac{5}{8}\)
\(y=\dfrac{7}{5}\)
a, 3/4 x y = 3/5 + 3/10
3/4 x y = 9/10
y = 9/10 : 3/4
y = 6/5
b, 3/5 : y = 3/4 - 2/5
3/5 : y = 7/20
y = 3/5 : 7/20
y = 12/7
![](https://rs.olm.vn/images/avt/0.png?1311)
a)2 + 5 + 11 + ... + 47+ 95
Tính chất : 5 = 2.2 + 1
11 = 5.2 + 1
Vậy các số của dãy là: 2 + 5 + 7 + 11 + 23 + 47 + 95
= (2 + 5 + 7) + (5 + 95) + (23 + 47)
= 14 + 100 + 70
= 184
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y x2+ y/2=10
=>yx2 + yx1/2 =10
=>yx (2+1/2)=10
=>y x 5/2=10
=>y=10 :5/2
=>y= 10x2/5
=>y=4
Trả lời: y=4
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\(x+\frac{1}{2}\times x=\frac{4}{5}\)
\(x\times\left(1+\frac{1}{2}\right)=\frac{4}{5}\)
\(x\times\frac{3}{2}=\frac{4}{5}\)
\(x=\frac{4}{5}:\frac{3}{2}\)
\(x=\frac{8}{15}\)
Vậy đáp án đúng là C
y+y*1/3*9/2+y*7/2
y+y*3/2+y*7/2=252
y*(1+3/2+7/2)=252
y* 6 =252
y =252:6
y =42
sai ngay bước đầu tiên nhưng cách làm sai phần đầu còn lại đúng