Các câu hỏi tương tự
Cho \(A=\frac{1}{5}-\frac{1}{7}+\frac{1}{17}-\frac{1}{31}+\frac{1}{65}-\frac{1}{127}\)
Chứng minh \(A<\frac{1}{10}\)
CMR: \(\frac{1}{5}-\frac{1}{7}+\frac{1}{17}-\frac{1}{31}+\frac{1}{65}-\frac{1}{127}< 10\)
Cho A=\(\frac{1}{5}-\frac{1}{7}+\frac{1}{17}-\frac{1}{31}+\frac{1}{65}-\frac{1}{127}.\)
So sánh A với \(\frac{1}{9}\)
Tìm số nguyên x
a) \(\frac{1}{3}+\frac{-2}{5}+\frac{1}{6}+\frac{-1}{5}\le x< \frac{-3}{4}+\frac{2}{7}+\frac{-1}{4}+\frac{3}{5}+\frac{5}{7}\)
b)\(\frac{5}{17}+\frac{-9}{4}+\frac{-26}{31}+\frac{12}{17}+\frac{-11}{31}< \frac{x}{9}\le\frac{-3}{7}+\frac{7}{15}+\frac{4}{-7}+\frac{8}{15}\)
\(M=\frac{\frac{2}{7}-\frac{2}{13}+\frac{2}{23}}{\frac{-5}{7}+\frac{5}{13}-\frac{5}{23}}+\frac{\frac{1}{17}-\frac{1}{23}+\frac{1}{31}}{\frac{3}{17}-\frac{3}{23}-\frac{3}{31}}\)
16 tính bằng cách hợp lí a) ( frac{1}{4}+ frac{-5}{13}) + ( frac{2}{11}+frac{-8}{13}+frac{3}{4})b) ( frac{21}{31}+frac{-16}{7}) +( frac{44}{53}+ frac{10}{31}) +frac{9}{53}c) frac{-5}{7}+frac{3}{4}+frac{-1}{5}+frac{-2}{7}+frac{1}{4}d) frac{-3}{31}+frac{-6}{17}+frac{1}{25}+frac{-28}{31}+frac{-11}{17}+frac{-1}{5}
Đọc tiếp
16 tính bằng cách hợp lí
a) ( \(\frac{1}{4}\)+ \(\frac{-5}{13}\)) + ( \(\frac{2}{11}+\frac{-8}{13}+\frac{3}{4}\))
b) ( \(\frac{21}{31}+\frac{-16}{7}\)) +( \(\frac{44}{53}\)+ \(\frac{10}{31}\)) +\(\frac{9}{53}\)
c) \(\frac{-5}{7}+\frac{3}{4}+\frac{-1}{5}+\frac{-2}{7}+\frac{1}{4}\)
d) \(\frac{-3}{31}+\frac{-6}{17}+\frac{1}{25}+\frac{-28}{31}+\frac{-11}{17}+\frac{-1}{5}\)
Bài 1:So sánh(bằng 2 cách):
\(A=\frac{10^{11}-1}{10^{12}-1}\)\(B=\frac{10^{10}+1}{10^{11}+1}\)
Bài 2:Chứng minh:
\(\frac{3}{5}< \frac{1}{31}+\frac{1}{32}+\frac{1}{33}+..........+\frac{1}{59}+\frac{1}{60}< \frac{4}{5}\)
1.Tính nhanh :a)Mfrac{17}{5}.frac{-31}{125}.frac{1}{2}.frac{10}{17}.frac{-1}{2^3}b)Nfrac{1}{7}.frac{5}{9}+frac{5}{9}.frac{2}{7}+frac{5}{9}.frac{1}{7}+frac{5}{9}.frac{3}{7}c)Pfrac{6}{7}.frac{8}{13}+frac{6}{9}.frac{9}{7}-frac{3}{13}.frac{6}{7}d)Qleft(frac{-9}{25}right)frac{53}{3}-left(frac{-5}{3}right)^2.frac{22}{3}2. Tính :a)Pleft(1-frac{1}{2}right).left(1-frac{1}{3}right).left(1-frac{1}{4}right)....left(1-frac{1}{1000}right)b)Qfrac{7}{3.5}+frac{7}{5.7}+frac{7}{7.9}+...+frac{7}{37.39}
Đọc tiếp
1.Tính nhanh :
a)M=\(\frac{17}{5}.\frac{-31}{125}.\frac{1}{2}.\frac{10}{17}.\frac{-1}{2^3}\)
b)N=\(\frac{1}{7}.\frac{5}{9}+\frac{5}{9}.\frac{2}{7}+\frac{5}{9}.\frac{1}{7}+\frac{5}{9}.\frac{3}{7}\)
c)P=\(\frac{6}{7}.\frac{8}{13}+\frac{6}{9}.\frac{9}{7}-\frac{3}{13}.\frac{6}{7}\)
d)Q=\(\left(\frac{-9}{25}\right)\frac{53}{3}-\left(\frac{-5}{3}\right)^2.\frac{22}{3}\)
2. Tính :
a)P=\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{1000}\right)\)
b)Q=\(\frac{7}{3.5}+\frac{7}{5.7}+\frac{7}{7.9}+...+\frac{7}{37.39}\)
Chứng minh rằng: Nếu \(\frac{a}{b}=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+\frac{1}{7}+\frac{1}{8}+\frac{1}{9}+\frac{1}{10}\)
Thì a chia hết cho 13