Cho A=1/1*2+1/3*4+1/5*6+...+1/99*100 CM 7/2<A<5/6
CM: \(\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{100^2}< \frac{1}{4}\)
CM : \(\frac{1}{6}<\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+......+\frac{1}{100^2}<\frac{1}{4}\)
Chứng minh:
1/22+1/42+1/62+....+1/1002 < 5/12
A=1/5^1+1/5^2+.....+1/100 CM 7/12<A<5/6
ai nhanh tick cho
Bài 1: CMR 3/1^2*2^2 + 5/2^2*3^2 + 7/3^2*4^2 + ....... + 19/9^2*10^2 bé hơn 1
Bài 2: CMR 1/3 + 2/3^2 Bài 1: CMR 3/1^2*2^2 + 5/2^2*3^2 + 7/3^2*4^2 + ....... + 19/9^2*10^2 bé hơn 3/4
Bài 3: Cho A= 1/1*2 + 1/3*4 + 1/5*6 + .... + 1/99*100. CMR 7/12 < A < 5/6
CM:1-1/2+1/3-1/4+1/5-1/6+.....+!/99-1/100=1/101+1/102+.+1/200
1) Tinh gia tri cua bieu thuc:
A=\(\frac{\left(1+2+...+100\right)\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{4}-\frac{1}{5}\right)\left(2,4.42-21.4,8\right)}{1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{100}}\)
B=\(\frac{4^6.9^5+6^9.120}{-8^4.3^{12}+6^{11}}\)
cm ;1/ 22 + 1/42+1/62+......+1/1002 < 1/2
