Ta có:$\frac{1}{31}$+$\frac{1}{32}$+....+ $\frac{1}{60}$
⇒$\frac{1}{31}$<$\frac{1}{60}$
$\frac{1}{32}$< $\frac{1}{60}$ Có 30 số $\frac{1}{60}$
......
$\frac{1}{60}$=$\frac{1}{60}$
⇒$\frac{1}{31}$+$\frac{1}{32}$+....+ $\frac{1}{60}$<30×$\frac{1}{60}$=$\frac{1}{2}$
Vậy $\frac{1}{31}$+$\frac{1}{32}$+....+ $\frac{1}{60}$<$\frac{1}{2}$
Đáp án:
Giải thích các bước giải:
Ta có: $\dfrac{1}{31}>\dfrac{1}{60}$ $;$ $\dfrac{1}{32}>\dfrac{1}{60}$ $;...;$ $\dfrac{1}{60}=\dfrac{1}{60}$
$ $
$⇒\dfrac{1}{31}+\dfrac{1}{32}+...+\dfrac{1}{60}>\dfrac{1}{60}+\dfrac{1}{60}+...+\dfrac{1}{60}$
$⇒\dfrac{1}{31}+\dfrac{1}{32}+...+\dfrac{1}{60}>\dfrac{30}{60}=\dfrac{1}{2}$
$⇒\dfrac{1}{31}+\dfrac{1}{32}+...+\dfrac{1}{60}>\dfrac{1}{2}$
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