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![](https://rs.olm.vn/images/avt/0.png?1311)
c) x+x-1+x-2+x-3+...+x-50=255
51x-(50+49+48+...+1)=255
51x-1275=255
51x=255+1275
51x=1530
x=1530:51
x=30
![](https://rs.olm.vn/images/avt/0.png?1311)
51x - [1+2+3+...+50] =255
=> 51x - 50 x 51 : 2 = 255
=> 51x - 1275 =255
=> 51x = 1530
=> x = 30
\(51x-\left(1+2+3+..+50\right)=255\)
\(51x-\frac{51.50}{2}=255\)
\(51x-1275=255\)
\(\Rightarrow51x=255+1275\)
\(\Rightarrow51x=1530\)
\(\Rightarrow x=30\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(\frac{1}{x}+\frac{2}{x}+\frac{3}{x}+\frac{4}{x}+...+\frac{50}{x}=255\)
\(\Rightarrow\frac{1+2+3+....+50}{x}=255\)
\(\Rightarrow\frac{\frac{50.51}{2}}{x}=255\)
\(\Rightarrow\frac{1275}{x}=255\Leftrightarrow x=\frac{1275}{255}=5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
bạn nguễn đăng khôi có thể làm có cả biểu thức a,b,c được ko
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![](https://rs.olm.vn/images/avt/0.png?1311)
4800:X+130/4+225=7,3x50\(\Rightarrow\)4800:x+130/4=110\(\Rightarrow\)x=4800:(110-130/4)\(\Rightarrow\)x=1920/31
![](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
x+(x-1)+(x-2)+...+(x-50)=255
x+(x+x+x+.....+x)-(1+2+3+...+50)=255
x+50x-1275=255
51x-1275
51x=1275+255
51x=1530
x=1530/51
x=30
trong phep chia cho 3 4 5 so du co the la bao nhieu