A= 5.(1/2 + 1/6+1/12+1/20+...+1/9506+1/9702+1/9900)
= 5. (1/1.2 + 1/2.3+1/3.4+1/4.5+...1/97.98+1/98.99+1/99.100)
= 5 .(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/97-1/98+1/98-1/99+1/99-1/100)
= 5.(1-1/100)=5. 99/100=99/20
A= 5.(1/2 + 1/6+1/12+1/20+...+1/9506+1/9702+1/9900)
= 5. (1/1.2 + 1/2.3+1/3.4+1/4.5+...1/97.98+1/98.99+1/99.100)
= 5 .(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/97-1/98+1/98-1/99+1/99-1/100)
= 5.(1-1/100)=5. 99/100=99/20
TÍNH:
A= \(\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+..........+\frac{9989}{9900}\)
tính tổng
\(100\cdot\)(\(1+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+.......+\frac{9899}{9900}\))
thực hiện phép tính
A=\(100.\left(1+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+...+\frac{9899}{9900}\right)\)
Cho A=\(\frac{3}{2}+\frac{13}{12}+\frac{21}{20}+...+\frac{9901}{9900}\)và B=\(\frac{5}{6}+\frac{19}{20}+\frac{41}{42}+...+\frac{10099}{10100}\)Tính A-B
A=1+2+3+4+5+...+99+100
B=\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{9900}\)
Tính giá trị biểu thức
2) K= \(\frac{1}{6}\)+\(\frac{1}{12}\)+\(\frac{1}{20}\)+...+ \(\frac{1}{9900}\)
3) L= \(\frac{5}{1.4}\)+\(\frac{5}{4.7}\)+ .... + \(\frac{5}{100.103}\)
Tính nhanh
\(\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+.....+\frac{9899}{9900}\)
Tính Tổng \(\frac{5}{2}\) + \(\frac{5}{6}\) \(\frac{5}{12}\)+ \(\frac{5}{20}\)+\(\frac{5}{42}\)+ ..... +\(\frac{5}{110}\)
\(A=\frac{7}{6}+\frac{13}{12}+\frac{21}{20}+\frac{31}{30}+...+\frac{9901}{9900}\)
\(B=\frac{2}{3}+\frac{5}{6}+\frac{9}{10}+\frac{14}{15}+...+\frac{4949}{4950}\)