\(A=1^3+2^3+3^3+4^3\)
\(A=1+8+27+64=100\)
\(A=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\)
\(\Rightarrow A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{99}-\frac{1}{100}\)
\(\Rightarrow A=1-\frac{1}{100}=\frac{99}{100}\)
A= 1/1x2 + 1/2x3 + 1/3x4 + .........+1/99x100
A=1/1x2 + 1/2x3 + ... + 1/99x100
Tính A
A = 1/1x2 + 1/2x3 +...+ 1/99x100
Tính A
Tính:
1/1x2 + 1/2x3 + ... + 1/99x100
Tinh: 1/1x2+1/2x3+1/3x4+...+1/99x100
3x - (1/1x2+1/2x3+.....+1/99x100)=1/1x2x3+1/2x3x4+......+1/18x19x20
6)chứng tỏ
a)1/1x2+1/2x3+...+1/9x10 <1
b)1/1x2+1/2x3+...+1/99x100 <1
a)4/1x5+1/5x9+1/9x13+1/13x17+1/17x21<1
Lưu ý:"x" là phép nhân
\(\frac{1}{1x2}+\frac{1}{2x3}+.....+\frac{1}{99x100}\)
chứng minh rằng:
1x2-1/2! + 2x3-1/3!+.....+99x100-1/100! <2
Chứng minh B/A thuộc Z
A= 1/1x2+1/2x3+...+1/99x100
B=2017/51+2017/52+...+2017/100
