`\frac{x-2}{12}+` `\frac{x-2}{20}+` `\frac{x-2}{30}+` `\frac{x-2}{42}+` `\frac{x-2}{56}+` `\frac{x-2}{72}=` `\frac{16}{9}`
Giải :
`\frac{x-2}{12}+` `\frac{x-2}{20}+``\frac{x-2}{30}+` `\frac{x-2}{42}+` `\frac{x-2}{56}+` `\frac{x-2}{72}=` `\frac{16}{9}`
`->` `(x-2)` `(\frac{1}{12}+` `\frac{1}{20}+` `\frac{1}{30}+` `\frac{1}{42}+` `\frac{1}{56}+` `\frac{1}{72})=` `\frac{16}{9}`
`->` `(x-2)` `(\frac{1}{3.4}+` `\frac{1}{4.5}+` `\frac{1}{5.6}+` `\frac{1}{6.7}+` `\frac{1}{7.8}+` `\frac{1}{8.9})=` `\frac{16}{9}`
`->` `(x-2)``(\frac{1}{3}``-\frac{1}{9})=` `\frac{16}{9}`
`->` `(x-2)` `\frac{2}{9}=` `\frac{16}{9}`
`->` `x-2` `=` `8`
`->` `x=` `10`
