\(S.2=\frac{2}{2.4}+\frac{2}{4.6}+...........+\frac{2}{98.100}\)
\(S.2=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+.....+\frac{1}{98}-\frac{1}{100}\)
\(S.2=\frac{1}{2}-\frac{1}{100}\)
\(S.2=\frac{49}{100}\)
\(S=\frac{49}{100}:2\)
\(S=\frac{49}{200}\)
S =\(\frac{1}{2\times4}\)+\(\frac{1}{4\times6}+\frac{1}{6\times8}+...+\frac{1}{96\times98}+\frac{1}{98\times100}\)
tính :\(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+\frac{1}{3\times4\times5}+\frac{1}{4\times5\times6}+\frac{1}{5\times6\times7}+\frac{1}{6\times7\times8}+\frac{1}{7\times8\times9}+\frac{1}{8\times9\times10}\)
\(\frac{1}{1\times4}+\frac{1}{4\times7}+\frac{1}{7\times10}+\frac{1}{10\times13}+\cdot\cdot\cdot+\frac{1}{81\times84}+\frac{1}{84\times87}\)= ?
\(\left(1+\frac{1}{2}\right)\cdot\left(1+\frac{1}{3}\right)\cdot\left(1+\frac{1}{4}\right)\cdot....\cdot\left(1+\frac{1}{98}\right)\cdot\left(1+\frac{1}{99}\right)=\)?
\(\frac{1}{2\times4}+\frac{1}{4\times6}+\frac{1}{6\times8}+...+\frac{1}{12\times14}=?\)
\(\frac{2\cdot x+1}{2}+\frac{4\cdot x+1}{4}+\frac{^{6\cdot x+1}}{6}=12\frac{11}{12}\)
TÍNH BẰNG CÁCH THUẬN TIỆN NHẤT
A)\(\frac{2}{3}\cdot\frac{4}{5}+\frac{1}{3}\cdot\frac{4}{5}=\)
B)\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\)
C)\(\frac{2}{3}\cdot\frac{4}{5}-\frac{1}{3}\cdot\frac{4}{5}=\)
D)\(\frac{1}{2}:\frac{3}{4}-\frac{1}{6}:\frac{3}{4}=\)
Tính nhanh:
\(\left(1+\frac{1}{100}\right)\cdot\left(1+\frac{1}{99}\right)\cdot\left(1+\frac{1}{98}\right)\cdot...\cdot\left(1+\frac{1}{2}\right)\)
. là nhân nhé còn ... là vâng vâng
Tinh bằng cách thuật tiện nhất
\(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\)
