tìm x biết `2/3.x - 70 10/11 : (131313/151515 + 131313/ 353535 + 131313/636363 + 1313131/ 999999) = -5`

`2/3 .x-70 10/11:(131313/151515+131313/353535+131313/636363+131313/999999)=-5`

`=>2/3 .x-780/11:({13xx10101}/{15xx10101}+{13xx10101}/{35xx10101}+{13xx10101}/{63xx10101}+{13xx10101}/{99xx10101})=-5`

`=>2/3 .x-780/11:(13/15+13/35+13/63+13/99)=-5`

`=>2/3 .x-780/11:13:(1/{3.5}+1/{5.7}+1/{7.9}+1/{9.11})=-5`

`=>2/3 .x-780/11 . 1/13 .2 : (2/{3.5}+2/{5.7}+2/{7.9}+2/{9.11})=-5`

`=>2/3 .x-780/143 .2:(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)=-5`

`=>2/3 .x-60/11 .2:(1/3-1/11)=-5`

`=>2/3 .x-120/11 : (11/33-3/33)=-5`

`=>2/3 .x-120/11:8/33=-5`

`=>2/3 .x-45=-5`

`=>2/3 .x=-5+45`

`=>2/3 .x=40`

`=>x=40:2/3`

`=>x=60`

`-` Vậy : `x=60.`

`#Sal_tSea`