Bài 1:
\(a,\left(x-\frac{1}{2}\right)\cdot\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+......+\frac{1}{90}\right)=\frac{1}{3}\)
\(b,\frac{1}{1\cdot6}+\frac{1}{6\cdot11}+.....+\frac{1}{96\cdot101}=\frac{1}{10\cdot x}\)
\(c,460+85\cdot4=\frac{x+175}{5}+30\)
\(d,\left(x-5\right)\cdot\left(10-9\frac{40}{41}\right):\left(1-\frac{81}{82}\right):\left(1-\frac{204}{205}\right)=2050\)