Tìm x, biết: \(\frac{3x}{2.5}\)+\(\frac{3x}{5.8}\)+\(\frac{3x}{8.11}\)+\(\frac{3x}{11.14}\)=\(\frac{1}{21}\)
\(\frac{3x}{2.5}+\frac{3x}{5.8}+\frac{3x}{8.11}+\frac{3x}{11.14}=\frac{1}{21}\)
Đề bài là tìm x nhé các bạn, các bạn giải giúp mik nhé!!
Bài làm
\(\frac{3x}{2.5}+\frac{3x}{5.8}+\frac{3x}{8.11}+\frac{3x}{11.14}=\frac{1}{21}\)
\(\Leftrightarrow\frac{x}{2}-\frac{x}{5}+\frac{x}{5}-\frac{x}{8}+\frac{x}{8}-\frac{x}{11}+\frac{x}{11}-\frac{x}{14}=\frac{1}{21}\)
\(\Leftrightarrow\frac{x}{2}-\frac{x}{14}=\frac{1}{21}\)
\(\Leftrightarrow\frac{7x}{14}-\frac{x}{14}=\frac{1}{21}\)
\(\Leftrightarrow\frac{6x}{14}=\frac{1}{21}\)
\(\Leftrightarrow126x=14\)
\(\Leftrightarrow x=\frac{1}{9}\)
Học tôt
Bài làm:
Ta có: \(\frac{3x}{2.5}+\frac{3x}{5.8}+\frac{3x}{8.11}+\frac{3x}{11.14}=\frac{1}{21}\)
\(\Leftrightarrow x\left(\frac{5-2}{2.5}+\frac{8-5}{5.8}+\frac{11-8}{8.11}+\frac{14-11}{11.14}\right)=\frac{1}{21}\)
\(\Leftrightarrow x\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}\right)=\frac{1}{21}\)
\(\Leftrightarrow x\left(\frac{1}{2}-\frac{1}{14}\right)=\frac{1}{21}\)
\(\Leftrightarrow\frac{3}{7}x=\frac{1}{21}\)
\(\Leftrightarrow x=\frac{1}{9}\)
Học tốt!!!!
Tìm x:
\(\frac{3x}{2.5}+\frac{3x}{5.8}+\frac{3x}{8.11}+\frac{3x}{8.11}=\frac{1}{21}\)
tìm x, biết:\(\frac{3x}{2.5}\)+\(\frac{3x}{5.8}\)+\(\frac{3x}{8.11}\)+\(\frac{3x}{11.14}\)=\(\frac{1}{21}\)
\(\frac{1}{2}-\frac{1}{14}=\frac{3}{7}\). Mà ở đây kết quả là \(\frac{1}{21}\)nên phân số phải nhóm ra ngoài là:
\(\frac{1}{21}:\frac{3}{7}=\frac{1}{9}\). Ta có:
\(\frac{1}{9}.\left(\frac{3x}{2.5}+\frac{3x}{5.8}+\frac{3x}{8.11}+\frac{3x}{11.14}\right)=\frac{1}{21}\). Suy ra 3x=9. Vậy x=3
Nhầm nha: Vì có 3x nên phân số nhóm ra ngoài là \(\frac{1}{3}\). Ta có tương tự. Suy ra 3x=3. Vậy x=1
Ta có 3x / 2.5 + 3x/5.8 + 3x/8.11 + 3x / 11.14 = 1/21
x ( 3/2.5 + 3/5.8 + 3/8.11 + 3/11 . 14) = 1/21
x( 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 + 1/11 - 1/14) = 1/21
x( 1/2 - 1/14) = 1/21
x= 1/21 : 3/7
x= 1/21 . 7/3
x= 1/9
tìm x biết 3x/2.5+3x/5.8+3x/8.11+3x/11.14 = 1/21
3x/2.5 + 3x/5.8+3x/8.11+3x/11.14 = 1/21
x(1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14) = 1/21
x(1/2-1/14) = 1/21
x . 3/7 = 1/21
=> x = 1/21 : 3/7
=> x = 1/9
Hihi mình giải zầy mk hk bik đúng hay sai
\(\frac{3x}{2.5}+\frac{3x}{5.8}+\frac{3x}{8.11}+\frac{3x}{11.14}=\frac{1}{21}\)
\(x.\left(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}\right)\)\(=\frac{1}{21}\)
\(x.\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}\right)\)\(=\frac{1}{21}\)
\(x.\left(\frac{1}{2}-\frac{1}{4}\right)\)\(=\frac{1}{21}\)
\(x.\frac{3}{7}=\frac{1}{21}\)
\(x=\frac{1}{21}:\frac{3}{7}\)
\(x=\frac{1}{9}\)
Tìm x biết: \(\dfrac{3x}{2.5}+\dfrac{3x}{5.8}+\dfrac{3x}{8.11}+\dfrac{3x}{11.14}=\dfrac{1}{21}\)
\(x\) \((\)\(\dfrac{3}{2.5}\) \(+
\) \(\dfrac{3}{5.8}\) \(+\) \(\dfrac{3}{8.11}\) \(+\) \(\dfrac{3}{11.14}\)\()\) \(=\) \(\dfrac{1}{21}\)
\(x\) \((\)\(\dfrac{1}{2}\) \(-\) \(\dfrac{1}{5}\) \(+\) \(\dfrac{1}{5}\) \(-\) \(\dfrac{1}{8}\) \(+\) \(\dfrac{1}{8}\) \(-\) \(\dfrac{1}{11}\) \(+\) \(\dfrac{1}{11}\) \(-\) \(\dfrac{1}{14}\)\()\) \(=\) \(\dfrac{1}{21}\)
\(x\) \((\)\(\dfrac{1}{2}\) \(-\) \(\dfrac{1}{14}\)\()\) \(=\) \(\dfrac{1}{21}\)
\(x\) x \(\dfrac{3}{7}\) \(=\) \(\dfrac{1}{21}\)
\(x\) \(=\) \(\dfrac{1}{21}\) \(:\) \(\dfrac{3}{7}\)
\(x\) \(=\) \(\dfrac{1}{9}\)
1.Tìm x:
3x/2.5 + 3x/5.8 + 3x/8.11 +3x/11.14 =1/21
Ta có : \(\frac{3x}{2\times5}+\frac{3x}{5\times8}+\frac{3x}{8\times11}+\frac{3x}{11\times14}=\frac{1}{21}\)
\(\Rightarrow x\times\left(\frac{3}{2\times5}+\frac{3}{5\times8}+\frac{3}{8\times11}+\frac{3}{11\times14}\right)=\frac{1}{21}\)
\(\Rightarrow x\times\left(\frac{1}{2\times5}+\frac{1}{5\times8}+\frac{1}{8\times11}+\frac{1}{11\times14}\right)=\frac{1}{21}\)
\(x\times\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}\right)=\frac{1}{21}\)
\(x\times\left(\frac{1}{2}-\frac{1}{14}\right)\) \(=\frac{1}{21}\)
\(x\times\frac{3}{7}\) \(=\frac{1}{21}\)
\(x\) \(=\frac{1}{21}\div\frac{3}{7}=\frac{1}{21}\times\frac{7}{3}\)
\(\Rightarrow x=\frac{1}{9}\)
Ta có 3x/2.5+3x/5.8+3x/8.11+3x/11.14=1/21
=>x(3/2.5+3/5.8+3/8.11+3/11.14)=1/21
=>3x(1/2.5+1/5.8+1/8.11+1/11.14)=1/21
=>3x(1/2-1/14)=1/21
=>3x.3/7=1/21
=>3x=1/21:3/7
=>3x=1
=>x=1:3=1/3
ta có : 3x / 2.5 + 3x / 5.8 + 3x / 8.11 + 3x / 11.14 = 1 / 21
=> 3x ( 1 /2.5 + 1 / 5.8 +1/8.11 + 1/11.14) = 1/21
=> 3x ( 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 + 1/11 - 1/14 ) = 1/21
3x ( 1/2 - 1/14 ) = 1/21
3x . 3/7 = 1/21
3x = 1/21 : 3/7
3x = 1/9
x = 1/9 : 3
x = 1/27
\(3x-\frac{15}{5.8}-\frac{15}{8.11}-\frac{15}{11.14}-...-\frac{15}{47.50}=2\frac{1}{10}\)
\(3x-\frac{15}{5\cdot8}-\frac{15}{8\cdot11}-\frac{15}{11\cdot14}-...-\frac{15}{47\cdot50}=2\frac{1}{10}\)
<=> \(3x-5\left(\frac{3}{5\cdot8}+\frac{3}{8\cdot11}+\frac{3}{11\cdot14}+...+\frac{3}{47\cdot50}\right)=\frac{21}{10}\)
<=> \(3x-5\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+...+\frac{1}{47}-\frac{1}{50}\right)=\frac{21}{10}\)
<=> \(3x-5\left(\frac{1}{5}-\frac{1}{50}\right)=\frac{21}{10}\)
<=> \(3x-5\cdot\frac{9}{50}=\frac{21}{10}\)
<=> \(3x-\frac{9}{10}=\frac{21}{10}\)
<=> \(3x=3\)
<=> \(x=1\)
Tìm x biết:
3x/2.5+3x/5.8+3x/8.11+3x/11.14=1/21
mn giải hộ mik nhe
`(3x)/(2.5)+(3x)/(5.8)+(3x)/(8.11)+(3x)/(11.14)=1/21`
`=>x(3(2.5)+3/(5.8)+3/(8.11)+3/(11.14))=1/21`
`=>x(1/2-1/5+1/5-1/8+1/8-1/11-1/14)=1/21`
`=>x*(1/2-1/14)=1/21`
`=>x*3/7=1/21`
`=>x=1/21:3/7=1/9`
Vậy `x=1/9`
3 x /2.5 + 3 x /5.8 + 3 x /8.11 + 3 x/11.14 = 1/21
⇒x (3 ( 2.5 ) + 3/5.8 + 3/8.11 + 3/11.14 ) = 1/21
⇒x (1/2 − 1/5 + 1/5 − 18 + 18 − 1/11 − 1/14 ) = 1/21
⇒x⋅ ( 1/2 − 1/14 ) = 1/21
⇒x ⋅ 3/7=1/21
⇒x . 3/7= 1/21
⇒x=1/21:3/7=1/9
Vậy x=1/9
\(\dfrac{3x}{2.5}+\dfrac{3x}{5.8}+\dfrac{3x}{8.11}+\dfrac{3x}{11.14}=\dfrac{1}{21}\)
\(x.\left(\dfrac{3}{2.5}+\dfrac{3}{5.8}+\dfrac{3}{8.11}+\dfrac{3}{11.14}\right)=\dfrac{1}{21}\)
\(x.\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{14}\right)=\dfrac{1}{21}\)
\(x.\left(\dfrac{1}{2}-\dfrac{1}{14}\right)=\dfrac{1}{21}\)
\(x.\dfrac{3}{7}=\dfrac{1}{21}\)
\(x=\dfrac{1}{21}:\dfrac{3}{7}\)
\(x=\dfrac{1}{9}\)
\(\frac{3x}{2.5}+\frac{3x}{5.8}+...+\frac{3x}{14.17}=\frac{1}{21}\)
\(\frac{3x}{2\cdot5}+\frac{3x}{5\cdot8}+.........+\frac{3x}{14\cdot17}=\frac{1}{21}\)
\(\Rightarrow3x\cdot\left(\frac{1}{2\cdot5}+\frac{1}{5\cdot7}+........+\frac{1}{14\cdot17}\right)=\frac{1}{21}\)
\(\Rightarrow3x\cdot\left[\frac{1}{3}\left(\frac{3}{2\cdot5}+\frac{3}{5\cdot7}+......+\frac{3}{14\cdot17}\right)\right]=\frac{1}{21}\)
\(\Rightarrow3x\cdot\left[\frac{1}{3}\cdot\left(\frac{1}{2}-\frac{1}{17}\right)\right]=\frac{1}{21}\)
\(\Rightarrow3x\cdot\left(\frac{1}{3}\cdot\frac{15}{34}\right)=\frac{1}{21}\)
\(\Rightarrow3x\cdot\frac{5}{34}=\frac{1}{21}\)\(\Rightarrow x=\frac{1}{21}:\frac{1}{34}:3\)
\(\Rightarrow x=\frac{34}{315}\)
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