Tìm x biết: (3/4+x) × 50%=0,8.
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a,\(\frac{10x125x4x25x8}{0,8x0,04x1,25x25+0,6524+0,3476}\)
=\(\frac{10x\left(125x8\right)x\left(4x25\right)}{\left(0,8x1,25\right)x\left(0,04x25\right)+\left(0,6524+0,3476\right)}\)
=\(\frac{10x1000x100}{1x1+1}\)
=\(\frac{1000000}{2}\)=\(500000\)
b,\(\frac{3}{4}\)x X + 1,25 x X + 50% x X = 12,5 x 0,8
0,75 x X + 1,25 x X + 0,5 x X = 10
(0,75 + 1,25 + 0,5) x X = 10
2,5 x X = 10
X = 10: 2,5 =4
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x .\)\(\dfrac{1}{2}+\dfrac{3}{2}.x=\dfrac{4}{5}\)
\(x.\)\((\dfrac{1}{2}+\dfrac{3}{2})=\dfrac{4}{5}\)
\(x.2=\)\(\dfrac{4}{5}\)
\(x=\)\(\dfrac{4}{5}:2\)
\(x=\)\(\dfrac{4}{10}=\dfrac{2}{5}\)
vậy \(x =\)\(\dfrac{2}{5}\)
\(x\times50\%+\dfrac{3}{2}\times x=0,8\)
\(\Leftrightarrow x\times\dfrac{50}{100}+\dfrac{3}{2}\times x=0,8\)
\(\Leftrightarrow x\times\dfrac{1}{2}+\dfrac{3}{2}\times x=\dfrac{4}{5}\)
\(\Leftrightarrow x\left(\dfrac{1}{2}+\dfrac{3}{2}\right)=\dfrac{4}{5}\)
\(\Leftrightarrow x\times2=\dfrac{4}{5}\)
\(\Leftrightarrow x=\dfrac{4}{5}:2\)
\(\Leftrightarrow x=\dfrac{4}{5}\times\dfrac{1}{2}\)
\(\Leftrightarrow x=\dfrac{2}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(-\frac{3}{7}+x=\frac{1}{3}\)
\(x=\frac{1}{3}+\frac{3}{7}\)
\(x=\frac{16}{21}\)
b)\(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)
\(\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}\)
\(\frac{1}{4}:x=-\frac{7}{20}\)
\(x=\frac{-7}{20}x\frac{1}{4}\)
\(x=-\frac{7}{80}\)
d)\(\left|x-3\right|=\frac{1}{2}\)
\(\Rightarrow\hept{\begin{cases}x-3=\frac{1}{2}\\x-3=\frac{-1}{2}\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{7}{2}\\x=\frac{5}{2}\end{cases}}\)
Mk bổ sung nha
c)\(1\frac{1}{3}:0,8=\frac{2}{3}:0,1x\)
\(\frac{5}{3}=\frac{2}{3}:0,1x\)
\(0,1x=\frac{2}{3}:\frac{5}{3}\)
\(0,1x=\frac{2}{5}\)
\(x=\frac{2}{5}:0,1\)
\(x=4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
15,4-(3x+0,8)*2=6
(3x+0,8)*2=15,4-6
3x+0,8=9,4/2
3x+0,8=4,7
3x=4,7-0,8
3x=3,9
x=3,9/3
x=1,3
![](https://rs.olm.vn/images/avt/0.png?1311)
` (3/4 +x) xx 50/100 = 8/10`
`( 3/4 + x) xx 1/2 = 4/5`
` 3/4 + x = 4/5 : 1/2`
` 3/4 + x = 4/5 xx2`
` 3/4 + x = 8/5`
` x = 8/5 - 3/4`
` x = 17/20`
![](https://rs.olm.vn/images/avt/0.png?1311)
=0,8x2x48+1,6x2+1,6x50
=1,6x48+1,6x2+1,6x50
=1,6x(48+2+50)
=1,6x100
=160
Đáp án + Giải thích các bước giải:
69
,
78
×
75
%
+
69
,
78
×
1
4
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69
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78
×
99
=
69
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78
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3
4
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69
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78
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1
4
+
69
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75
×
99
=
69
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78
×
(
3
4
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1
4
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99
)
=
69
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78
×
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1
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99
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69
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78
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100
=
6978
\(\left(\frac{3}{4}+x\right)\times50\%=0,8\)
\(\frac{3}{4}+x=0,8:50\%\)
\(\frac{3}{4}+x=0,4\)
\(x=0,4-\frac{3}{4}\)
\(x=\frac{-7}{20}\)