Cho: \(A=\frac{1}{2}.\frac{3}{4}.\frac{5}{6}....\frac{79}{80}\)
Chứng minh \(A<\frac{1}{9}\)
Bài 1 : Cho A = \(\frac{1}{2}.\frac{3}{4}.\frac{5}{6}.\frac{7}{8}...\frac{79}{80}\)
Chứng minh rằng A < \(\frac{1}{9}\)
Bài 4 : Chứng minh rằng: 1.3.5.7....19 = \(\frac{11}{2}.\frac{12}{2}.\frac{13}{2}...\frac{20}{2}\)
Cho biểu thức:
\(C=\frac{1}{2}x\frac{3}{4}x\frac{5}{6}x.....x\frac{79}{80}\)
Chứng minh C bé hơn \(\frac{1}{9}\)
Cho \(A=\frac{1}{2}.\frac{3}{4}.\frac{5}{6}...\frac{79}{80}\)và \(\frac{1}{9}\). Hãy so sánh
Cho \(A=\frac{1}{2}.\frac{3}{4}.\frac{5}{6}.\frac{7}{8}.....\frac{79}{80}.CMR\)
\(A<\frac{1}{9}\)
Tính
A=\(\frac{1}{2}.\frac{3}{4}.\frac{5}{6}.\frac{7}{8}.......................\frac{79}{80}\)
Bài 1 : Tính
Cho A =\(\frac{1}{31}+\frac{1}{32}+\frac{1}{33}+......+\frac{1}{60}>\frac{7}{12}\)
B = \(\frac{1}{3^2}+\frac{1}{3^2}+\frac{1}{5^2}+......+\frac{ }{50^{21}}\)
CMR B >\(\frac{1}{4}\)và B < \(\frac{4}{9}\)
C = \(\frac{1}{2}.\frac{3}{4}.\frac{5}{6}.\frac{7}{8}.......\frac{79}{80}< \frac{1}{9}\)
CHO TÍCH :A= \(\frac{1}{2}\)X\(\frac{3}{4}\)X\(\frac{5}{6}\)X....X\(\frac{79}{80}\) . CMR : A<\(\frac{1}{9}\)
