VD7
a) Ta có:
$\frac{215}{317}$ <1
$\frac{152}{131}$ >1
=>$\frac{152}{131}$ >1 > $\frac{215}{317}$
Vậy $\frac{152}{131}$>$\frac{215}{317}$
b) Ta có:
1-$\frac{2017}{2018}$ =$\frac{1}{2018}$
1-$\frac{2015}{2016}$ = $\frac{1}{2016}$
Mà $\frac{1}{2018}$<$\frac{1}{2016}$
=>$\frac{2017}{2018}$>$\frac{2015}{2016}$
c) Ta có:
$\frac{-89}{75}$< -1
$\frac{-31}{87}$>-1
=>$\frac{-31}{87}$>$\frac{-89}{75}$
d/ Ta có:
$\frac{-1989}{1991}$ > -1
$\frac{-2001}{2000}$ <-1
=>$\frac{-2001}{2000}$<$\frac{-1989}{1991}$
