Ta có : \(\frac{2}{3}x-70\frac{10}{11}(\frac{131313}{151515}+\frac{131313}{353535}+\frac{131313}{999999})=-5\)
\(\frac{2}{3}x-70\frac{10}{11}\cdot(\frac{13}{15}+\frac{13}{35}+\frac{13}{99})=-5\)
\(\frac{2}{3}x-70\frac{10}{11}\cdot(\frac{13}{3\cdot5}+\frac{13}{5\cdot7}+\frac{13}{9\cdot11})=-5\)
\(\frac{2}{3}x-70\frac{10}{11}\cdot\left[\frac{13}{2}\cdot(\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+\frac{2}{9\cdot11})\right]=-5\)
\(\frac{2}{3}x-70\frac{10}{11}\cdot\left[\frac{13}{2}\cdot(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11})\right]=-5\)
\(\frac{2}{3}x-70\frac{10}{11}\cdot[\frac{13}{2}\cdot(\frac{1}{3}-\frac{1}{11})]=-5\)
\(\frac{2}{3}x-70\frac{10}{11}\cdot\left[\frac{13}{2}\cdot\frac{8}{33}\right]=-5\)
\(\frac{2}{3}x-\frac{780}{11}\cdot\frac{52}{33}=-5\)
\(\frac{2}{3}x-\frac{13520}{121}=-5\)
Rồi còn khúc đó bạn tự làm
