\(\frac{F}{2}=\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{380}\)
\(\frac{F}{2}=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{19.20}\)
\(\frac{F}{2}=\frac{3-2}{2.3}+\frac{4-3}{3.5}+\frac{5-4}{4.5}+...+\frac{20-19}{19.20}\)
\(\frac{F}{2}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{19}-\frac{1}{20}\)
\(\frac{F}{2}=\frac{1}{2}-\frac{1}{20}=\frac{9}{20}\Rightarrow F=\frac{18}{20}=\frac{9}{10}\)
Tinh gia tri cua bieu thuc \(D=\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}\)
Nho giai va trinh bay cach lam cho minh luon nha ^_^
Tinh gia tri cac bieu thuc sau
B= \(\frac{10}{2.7}+\frac{10}{7.12}+...+\frac{10}{502.507}\)
C= \(\frac{1}{18}+\frac{1}{54}+\frac{1}{108}+...+\frac{1}{990}\)
Tinh gia tri cac bieu thuc sau
a) A = \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\)
Tinh hop ly gia tri cac bieu thuc sau
c) \(6\frac{5}{12}:2\frac{3}{4}+11\frac{1}{4}.\left(\frac{1}{3}-\frac{1}{5}\right)\)
d) \(\left(\frac{3}{5}+0,415-\frac{3}{200}\right).2\frac{2}{3}.0,25\)
Tinh gia tri cua bieu thuc \(D=\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{200}\)
Nho giai va tring bay cach lam cho minh luon nha ^_^
Tinh hop ly cac gia tri bieu thuc sau
a) \(4\frac{8}{23}+5\frac{7}{8}-9\frac{8}{23}\)
b)\(6\frac{3}{8}+5\frac{1}{2}\)
Tinh gia tri bieu thuc :
\(\left(\frac{1}{99}+\frac{12}{999}+\frac{123}{999}\right)\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
Tinh gia tri cac bieu thuc sau
D = \(\frac{1}{6.10}+\frac{1}{10.14}+...+\frac{1}{402.406}\)
E = \(\frac{4}{5.8}+\frac{4}{8.11}+...+\frac{4}{305.308}\)
Tinh hop ly gia tri cac bieu thuc sau
a) \(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{2}:\frac{7}{12}\right).\frac{4}{5}\)
b) \(\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)
