Ta có:
\(\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\)\(\times\)\(\left(\frac{1}{3}-\frac{1}{30}-\frac{1}{5}-\frac{1}{10}\right)\)
= \(\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\)\(\times\)\(\left(\frac{10}{30}-\frac{1}{30}-\frac{6}{30}-\frac{3}{30}\right)\)
= \(\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\)\(\times\)\(\left(\frac{10-1-6-3}{30}\right)\)
= \(\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\)\(\times\)\(0\)
= \(0\)
ta có \(\frac{1}{3}-\frac{1}{30}-\frac{1}{5}-\frac{1}{10}=\frac{10-1-6-3}{30}=\frac{0}{30}=0\)
=>\(\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)x\left(\frac{1}{3}-\frac{1}{30}-\frac{1}{5}-\frac{1}{10}\right)=0\)
\(\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\times\left(\frac{1}{3}-\frac{1}{30}-\frac{1}{5}-\frac{1}{10}\right)\)
\(=\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\times\left(\frac{10}{30}-\frac{1}{30}-\frac{6}{30}-\frac{3}{30}\right)\)
\(=\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\times\left(\frac{10-1-6-3}{30}\right)\)
\(=\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\times\frac{0}{30}\)
\(=\left(\frac{1}{21}+\frac{1}{210}+\frac{1}{2010}\right)\times0\)
\(=0\)