Ta có : \(\frac{5.5}{1.6}+\frac{5.5}{6.11}+\frac{5.5}{11.16}+\frac{5.5}{16.21}\)
\(=5\left(\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+\frac{5}{16.21}\right)\)
\(=5\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}\right)\)
\(=5\left(1-\frac{1}{21}\right)\)
\(=5.\frac{20}{21}=\frac{100}{21}\)
Đây là câu trả lời của Đinh Nguyễn Nguyệt Hà
\(A=\frac{5.2}{1.6}+\frac{5.2}{6.11}+\frac{5.2}{11.16}+\frac{5.2}{16.21}+\frac{5.2}{21.26}+\frac{5.2}{26.31}\)
\(\frac{A}{2}=\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+\frac{5}{16.21}+\frac{5}{21.26}+\frac{5}{26.31}\)
\(=1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+\frac{1}{26}-\frac{1}{31}\)
\(=1-\frac{1}{31}=\frac{30}{31}\)
\(\Rightarrow A=\frac{30}{31}.2=\frac{60}{31}\)
Nếu tử là 52 thì cậu chuyển thành 5.5 rồi chuyển 5 sang vế trái thành A/5 nha, cũng giống như trên thui!!!!!!!!
CHỨNG MINH RẰNG: \(\frac{1}{1.2}\)+ \(\frac{1}{3.4}\)+ \(\frac{1}{5.6}\)+ \(\frac{1}{7.8}\)+ \(\frac{1}{9.10}\)+ ......................+\(\frac{1}{17.18}\)> \(\frac{9}{19}\)
tính tong 100 so hang dau tien cua day: \(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+\frac{1}{16.21}+.....\)
(x+3).(2y-1)=9
S=\(\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}\)
S=\(\frac{1}{2.2}+\frac{1}{3.3}+\frac{1}{4.4}+\frac{1}{5.5}+...+\frac{1}{49.49}+\frac{1}{50.50}\)=?
Cho A = \(\frac{1}{5.5}\)+\(\frac{1}{6.6}\)+ ...........+\(\frac{1}{100.100}\)Chứng minh A >\(\frac{1}{6}\)và >\(\frac{1}{4}\)
TÍNH TỔNG :
a) \(\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{24.25}\)
b) \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{97.99}\)
c) \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{49.51}\)
d) \(\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}+\frac{5^2}{26.31}\)
Tìm x, biết:
\(\frac{5x}{1.6}+\frac{5x}{6.11}+\frac{5x}{11.16}+\frac{5x}{16.21}=\frac{1}{25}\)
Các bạn giải cụ thể giùm mình nha
Chứng minh rằng:
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}\)
