$\frac{x-2}{12}$ +$\frac{x-2}{20}$ +$\frac{x-2}{30}$ +$\frac{x-2}{42}$ +$\frac{x-2}{56}$ +$\frac{x-2}{72}$ =$\frac{16}{9}$
$\frac{x-2}{12}$ +$\frac{x-2}{20}$ +$\frac{x-2}{30}$ +$\frac{x-2}{42}$ +$\frac{x-2}{56}$ +$\frac{x-2}{72}$ =$\frac{16}{9}$
Đáp án:
`x=10`
Giải thích các bước giải:
`(x-2)/12 + (x-2)/20 + (x-2)/30 + (x-2)/42 + (x-2)/56 + (x-2)/72 = 16/9`
`to (x-2) . (1/12+1/20+1/30+1/42+1/56+1/72)=16/9`
`to (x-2) . (1/(3.4)+1/(4.5)+1/(5.6)+1/(6.7)+1/(7.8)+1/(8.9))=16/9`
`to (x-2).(1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9)=16/9`
`to (x-2).(1/3-1/9)=16/9`
`to (x-2) . 2/9=16/9`
`to x-2 = 16/9 : 2/9=8`
`to x=10`
Vậy `x=10`
`\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`