Tham khảo
Sửa:`\frac{x+257}{30}→\frac{x+247}{30}`
`⇒\frac{x+1}{156}+\frac{x+2}{155}+\frac{x+3}{154}+\frac{x+257}{30}=0`
`⇒(\frac{x+1}{156}+1)+(\frac{x+2}{155}+1)+(\frac{x+3}{154}+1)+(\frac{x+257}{30}-3)=0`
`⇒\frac{x+157}{156}+\frac{x+157}{155}+\frac{x+157}{154}+\frac{x+157}{30}=0`
`⇒(x+157)(\frac{1}{156}+\frac{1}{155}+\frac{1}{154}+\frac{1}{30})=0`
Do `\frac{1}{156}+\frac{1}{155}+\frac{1}{154}+\frac{1}{30} \ne 0`
`⇔x+157=0`
`⇔x=-157`
`\text{©CBT}`
