Nhan xet:
\(\frac{1}{2^2}< \frac{1}{2.3}=\frac{1}{2}-\frac{1}{3}\)
\(\frac{1}{3^2}< \frac{1}{3.4}=\frac{1}{3}-\frac{1}{4}\)
\(\frac{1}{4^2}< \frac{1}{4.5}=\frac{1}{4}-\frac{1}{5}\)
....
\(\frac{1}{100^2}< \frac{1}{100.101}=\frac{1}{100}-\frac{1}{101}\)
Vay:
\(\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{100^2}< \frac{1}{2}-\frac{1}{101}=\frac{99}{202}< \frac{3}{4}\)
S=1/3+2/3^2+3/3^3+4/3^4+..................+100/3^100. So sánh S với 1/5
Cho \(S=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{99^2}+\frac{1}{100^2}\)
So sánh S với 1
So sánh S=1/2+2/2^2+3/2^+1)3+4/2^4+.....+100/2^100 với 2
Cho S=1+3^2+3^4+3^6+.......+3^98+3^100.So sánh: 8S+1 với 2^152
Cho S = \(\dfrac{1}{3}-\dfrac{2}{3^2}+\dfrac{3}{3^3}-\dfrac{4}{3^4}+....+\dfrac{99}{3^{99}}-\dfrac{100}{3^{100}}\) so sánh S và \(\dfrac{1}{5}\)
cho s=1/3-2/32+3/33-4/34+........+99/399-100/3100
so sánh s với 1/5
Cho S=1+3^2+3^4+3^6+.....+3^98+3^100
So sánh 8S với 2^152
s=1-3+3^2-3^3+...+100/3^100 hãy so sánh s với 1/5
\(S=\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+...+\dfrac{1}{3^{100}}\) so sánh S với \(\dfrac{1}{2}\)
