Các câu hỏi tương tự
Cho A=1/3^2+1/4^2+1/5^2+...+1/50^2
Chung to rang a,A>1=4 b,A>4/9
Cho A=1/3^2+1/4^2+1/5^2+...+1/50^2
Chung to rang 1/4<M<4/9
Cho A=1/3^2+1/4^2+1/5^2+...+1/50^2
Chung to rang 1/4<M<4/9
Cho A=1/3^2+1/4^2+1/5^2+...+1/50^2
Chung to rang 1/4<M<4/9
a,A=1/1^2+1/2^2+1/3^2+1/4^2+...+1/50^2.chung minh rang a<2
b;2^1+2^2+2^3+...+2^30.chung minh rang B chia het cho21
Cho A = 1/32+1/42+1/52+.....+1/502 . Chứng minh rằng :
a) A > 1/4
b) A < 4/9
CHo A=1/3^2+1/4^2+1/5^2+...+1/50^2. Chứng tỏ rằng 1/4<A<4/9
Cho A = 1/3^2 + 1/4^2 + 1/5^2 +...+ 1/50^2
Chung minh 1/4 < A < 4/9
A=1/3^2+1/4^2+1/5^2+................+1/50^2
Chứng minh rằng:a)A>1/4 b)A<4/9