X + X x 1/4 : 2/7 + X : 2/9 = 255
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+x\times\dfrac{1}{4}:\dfrac{2}{7}+x:\dfrac{2}{9}=255\)
\(x+x\times\dfrac{7}{8}+x\times\dfrac{9}{2}=255\)
\(x\times\left(1+\dfrac{7}{8}+\dfrac{9}{2}\right)=255\)
\(x\times\dfrac{51}{8}=255\)
\(x=255:\dfrac{51}{8}\)
\(x=255\times\dfrac{8}{51}\)
\(x=40\)
\(x+x\times\dfrac{1}{4}:\dfrac{2}{7}+x:\dfrac{2}{9}=255\)
\(x+x\times\dfrac{7}{8}+x\times\dfrac{9}{2}=255\)
\(x+\left(1+\dfrac{7}{8}+\dfrac{9}{2}\right)=255\)
\(x\times\dfrac{51}{8}=255\)
\(x=255:\dfrac{51}{8}\left(255\times\dfrac{8}{51}\right)\)
\(x=40\)
tk cho mk nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
x + x * 1/4 : 2/7 + x : 2/9 = 255
x + x * 1/4 * 7/2 + x * 9/2 = 255
x + x * 7/8 + x * 9/2 = 255
x * ( 1 + 7/8 + 9/2 ) = 255
x * (8/8 + 7/8 + 36/8 ) = 255
x * 51/8 = 255
x = 255 : 51/8
x = 255* 8/51
x = 40
Chúc bạn học tốt!
x + x × 1/4 : 2/7 + x : 2/9 = 255
x + x × 1/4 × 7/2 + x × 9/2 = 255
x + x × 7/8 + x × 9/2 = 255
x × (1 + 7/8 + 9/2) = 255
x × (8/8 + 7/8 + 36/8) = 255
x × 51/8 = 255
x = 255 : 51/8
x = 255 × 8/51
x = 40
![](https://rs.olm.vn/images/avt/0.png?1311)
x + x × 1/4 : 2/7 + x : 2/9 = 255
x + x × 1/4 × 7/2 + x × 9/2 = 255
x + x × 7/8 + x × 9/2 = 255
x × (1 + 7/8 + 9/2) = 255
x × (8/8 + 7/8 + 36/8) = 255
x × 51/8 = 255
x = 255 : 51/8
x = 255 × 8/51
x = 40
x + x × 1/4 : 2/7 + x : 2/9 = 255
x + x × 1/4 × 7/2 + x × 9/2 = 255
x + x × 7/8 + x × 9/2 = 255
x × (1 + 7/8 + 9/2) = 255
x × (8/8 + 7/8 + 36/8) = 255
x × 51/8 = 255
x = 255 : 51/8
x = 255 × 8/51
x = 40
Vậy x = 40
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
$x+x\times \frac{1}{4}: \frac{2}{7}+x: \frac{2}{9}=255$
$x+x\times \frac{7}{8}+x\times \frac{9}{2}=255$
$x\times (1+\frac{7}{8}+\frac{9}{2})=255$
$x\times \frac{51}{8}=255$
$x=255: \frac{51}{8}=40$
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x +x\cdot\frac{1}{4}\text{ : }\frac{2}{7}+x\text{ : }\frac{2}{9}=255\)
\(x+x\cdot0,25\text{ : }0,285714286+x\text{ : }0,222222222=255\)
\(x+x\cdot\left(0,25\text{ : }0,285714286\right)+x\text{ }\text{ : }0,222222222=255\)
\(x+x\cdot0,874999999+x\text{ : }0,222222222=255\)
\(x\cdot3\cdot\left(0,874999999\text{ : }0,222222222\right)=255\)
\(x\cdot3\cdot3,9375=255\)
\(x\cdot3=255\text{ : }3,9375\)
\(x\cdot3=64,7619048\)
\(x=64,7619048\text{ : }3\)
\(x=21,5873016\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+x.\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\)
\(=x+x.\left(\frac{1}{4}:\frac{2}{7}\right)+x:\frac{2}{9}=255\)
\(=x+x.\frac{7}{8}+x:\frac{2}{9}=255\)
\(=x+x.\frac{7}{8}+x.\frac{9}{2}=255\)
\(=x+x.\left(\frac{7}{8}+\frac{9}{2}\right)=255\)
\(=x+x.\frac{43}{8}=255\)
\(\Leftrightarrow x=40\)
chúc bạn học giỏi
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x+x\times\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\)
\(x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)
\(x\times\left(1+\frac{1}{4}\times\frac{7}{2}+\frac{9}{2}\right)=255\)
\(x\times\frac{51}{38}=255\)
\(x=255:\frac{51}{38}\)
\(x=190\)
\(x+x.\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\)
\(\Rightarrow x+x.\frac{1}{4}.\frac{7}{2}+x.\frac{9}{2}=255\)
\(\Rightarrow x+x.\frac{7}{8}+x.\frac{9}{2}=255\)
\(\Rightarrow x.\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)
\(\Rightarrow x.\frac{51}{8}=255\)
\(\Rightarrow x=255:\frac{51}{8}\)
\(\Rightarrow x=40\)
Vậy x = 40
_Chúc bạn học tốt_
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(x+x\times\frac{1}{4}\div\frac{2}{7}+x\div\frac{2}{9}=255\)
\(\Rightarrow x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)
\(\Rightarrow x+x\times\frac{7}{8}+x\times\frac{9}{2}=255\)
\(\Rightarrow x\times\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)
\(\Rightarrow x\times\frac{51}{8}=255\)
\(\Rightarrow x=255\div\frac{51}{8}\)
\(\Rightarrow x=40\)
Vậy x = 40
b) \(1\frac{1}{21}\div\left(15,75-15\frac{1}{5}\right)+2\frac{1}{12}\div\left(7\frac{3}{4}-7,25\right)\)
\(=\frac{22}{21}\div\left(15,75-\frac{76}{5}\right)+\frac{25}{12}\div\left(\frac{31}{4}-7,25\right)\)
\(=\frac{22}{21}\div\frac{11}{20}+\frac{25}{12}\div\frac{1}{2}\)
\(=\frac{40}{21}+\frac{25}{6}\)
\(=\frac{85}{14}\)
_Chúc bạn học tốt_
X + X x 1/4 : 2/7 + x : 2/9 = 225
X + X x 1/4 x 7/2 + X x 9/2 = 225
X + X x 7/8 + X x 9/2 = 225
X x ( 1 + 7/8 + 9/2 ) = 225
X x 51/8 = 225
X = 225 : 51/8
X = 600/17
X+X*1/4:2/7+X:2/9=255
X+X*1/4*+7/2+X*9/2=255
X+X*7/8+X*9/2=255
X*(1+7/8+9/2)=255
X*(8/8+7/8+36/8)=255
X*51/8=255
X=255:51/8
X=255*8/51
X=40