\(\frac{1.3.5...79}{2.4.6...80}\)= \(\frac{1.3.5...79}{\left(1.2\right).\left(2.2\right).\left(3.2\right)...\left(40.2\right)}\).\(\frac{1.3.5...79}{\left(1.2.3.4...40\right).\left(2.2.2.2...2.2\right)}\)=\(\frac{1.3.5...79}{\left(1.3.5...39\right).\left(2.4.6...40\right).2^{40}}\)<1/9
Cho \(A=\frac{1}{2}.\frac{3}{4}.\frac{5}{6}....\frac{79}{80}\)
Chứng minh \(A<\frac{1}{9}\)
A=\(\frac{1}{2}\cdot\frac{3}{4}\cdot\frac{5}{6}\cdot...\cdot\frac{79}{80}.CM:A<\frac{1}{9}\)
\(A=\frac{1}{2}\cdot\frac{3}{4}\cdot\frac{5}{6}\cdot...\cdot\frac{79}{80}:CM:A<\frac{1}{9}\)
Tính A = \(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+.........+\frac{1}{31}\)
Chứng minh A < 4
Giải chi tiết giúp mk bài này với: Tính hợp lý :
\(A=\left(-\frac{2}{9}\right)-\left(-\frac{1}{121}\right)+\left(-\frac{3}{5}\right)+\left(-\frac{1}{2}\right)-\left(-1\frac{13}{18}\right)-\frac{1}{7}-\frac{9}{35}\)
\(B=0,75+\frac{3}{5}+\left(\frac{2}{9}-1\frac{3}{5}+1\frac{1}{4}\right)\)
\(C=1-2+3-4+...+79-80\)
\(a=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+......+\frac{1}{49}-\frac{1}{50}\)\(\frac{1}{50}\) Chứng minh rằng a<\(\frac{5}{6}\)
cho \(A=\frac{1}{2}\cdot\frac{3}{4}\cdot...\cdot\frac{79}{80}\)
\(CM:A<\frac{1}{9}\)
Bài 1:Tìm x
a) b)
c)
d)
e)
Bài 2:Tính giá trị
A= B=
C=
D=
E= F=
Bài 3:Tính
A = a - b + c biết B = a - b - c với
Cho biểu thức A= \(\frac{2}{1}\times\frac{4}{3}\times\frac{6}{5}\times\frac{8}{7}\times\frac{10}{9}\times...\times\frac{100}{99}\)Chứng minh rằng 12<A<13
