\(\dfrac{x-2}{28}+\dfrac{x-3}{27}+\dfrac{x-7}{23}=3\\ \Leftrightarrow\left(\dfrac{x-2}{28}-1\right)+\left(\dfrac{x-3}{27}-1\right)+\left(\dfrac{x-7}{23}-1\right)=0\\ \Leftrightarrow\dfrac{x-30}{28}+\dfrac{x-30}{27}+\dfrac{x-30}{23}=0\\ \Leftrightarrow\left(x-30\right)\left(\dfrac{1}{28}+\dfrac{1}{27}+\dfrac{1}{23}\right)=0\\ \Leftrightarrow x=30\)
`[x-2]/28+[x-3]/27+[x-7]/23=3`
`=>[x-2]/28-1+[x-3]/27-1+[x-7]/23-1=3-1-1-1`
`=>[x-2-28]/28+[x-3-27]/27+[x-7-23]/23=0`
`=>[x-30]/28+[x-30]/27+[x-30]/23=0`
`=>(x-30)(1/28+1/27+1/23)=0`
Mà `1/28+1/27+1/23 \ne 0`
`=>x-30=0`
`=>x=30`
Vậy `x=30`
\(\Leftrightarrow\left(\dfrac{x-2}{28}-1\right)+\left(\dfrac{x-3}{27}-1\right)+\left(\dfrac{x-7}{23}-1\right)=0\)
\(\Leftrightarrow\left(x-30\right)\left(\dfrac{1}{28}+\dfrac{1}{27}+\dfrac{1}{23}\right)=0\)
\(\Leftrightarrow x-30=0\left(vì\left(\dfrac{1}{28}+\dfrac{1}{27}+\dfrac{1}{23}>0\right)\right)\)
\(\Leftrightarrow x=30\)
Ta có: \(\dfrac{x-2}{28}+\dfrac{x-3}{27}+\dfrac{x-7}{23}=3\)
\(\Rightarrow\dfrac{x-2}{28}-1+\dfrac{x-3}{27}-1+\dfrac{x-7}{23}-1=0\)
\(\Rightarrow\dfrac{x-30}{28}+\dfrac{x-30}{27}+\dfrac{x-30}{23}=0\)
\(\Rightarrow\left(x-30\right)\left(\dfrac{1}{28}+\dfrac{1}{27}+\dfrac{1}{23}\right)=0\)
\(\Rightarrow x=30\)
