TÍNH NHANH: \(S=\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+.......+\frac{1}{190}\)
Tính tổng:
a, S = \(\frac{1}{2}\)+ \(\frac{1}{4}\)+ \(\frac{1}{8}\)+ \(\frac{1}{16}\)+ \(\frac{1}{32}\)+ \(\frac{1}{64}\)+ \(\frac{1}{128}\)+ \(\frac{1}{256}\)
b, A = 1 + \(\frac{1}{3}\)+ \(\frac{1}{6}\)+ \(\frac{1}{10}\)+ \(\frac{1}{15}\)+ \(\frac{1}{21}\)+ \(\frac{1}{28}\)+ \(\frac{1}{36}\)+ \(\frac{1}{45}\)
Tinh A biet : A=\(\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+...+\frac{1}{120}.\)
Tính:
a) \(A=\frac{\frac{\frac{1}{2}+\frac{1}{3}+\frac{1}{7}}{\frac{8}{2}+\frac{8}{3}+\frac{8}{7}}}{\frac{\frac{1}{7}+\frac{1}{8}+\frac{1}{92}}{\frac{4}{7}+\frac{4}{8}+\frac{4}{92}}}\) ;b) \(B=\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+.........+\frac{1}{120}\)
Giúp mình vs mình tick cho.
Tính tổng sau bằng cách nhanh nhất:
\(\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{190}\)
Giúp mình với, mình đag cần gấp!!!
Tính hợp lý:
\(\frac{16}{9}-\frac{1}{36}-\frac{1}{28}-\frac{1}{21}-\frac{1}{15}-\frac{1}{10}-\frac{1}{6}-\frac{1}{3}-1\)
Tính giá trị biểu thức
S=(\(\frac{1}{3}\)+\(\frac{1}{6}\)+\(\frac{1}{10}\)+\(\frac{1}{15}\))-(\(\frac{1}{21}\)+\(\frac{1}{28}\)+\(\frac{1}{36}\)+\(\frac{1}{45}\))
Tính nhanh nếu có thể:
a)
\(\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}+\frac{1}{143}+\frac{1}{195}\)
b)
\(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}+\frac{1}{55}+\frac{1}{66}\)
1+\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}\)