Ta có:

a)

$\frac{5}{6}−(\frac{1}{6})^{2}= \frac{29}{36}$

$(\frac{5}{6}−\frac{1}{6})^{2}= \frac{4}{9} = \frac{16}{36}$;

$\frac{29}{36}>\frac{16}{36}$

=>$\frac{5}{6}−(\frac{1}{6})^{2} > (\frac{5}{6}−\frac{1}{6})^{2}$;

b)

$250 . (\frac{5}{6}−\frac{1}{6})^{2} = \frac{18}{5}$

$250 . (\frac{1}{5})^{2}−\frac{1}{6} = \frac{59}{6}$;

Do $\frac{18}{5}< \frac{59}{6}$

=> $250 . (\frac{5}{6}−\frac{1}{6})^{2} < 250 . (\frac{1}{5})^{2}−\frac{1}{6}$;

c)

$3\frac{1}{5} : 1,5 + 4\frac{2}{5} : 1,5 = (3\frac{1}{5} + 4\frac{2}{5}) : 1,5$;

d)

$(\frac{9}{25}−2,18):(3\frac{4}{5})+0,2) = \frac{-91}{200}$

$ \frac{9}{25} : 3\frac{4}{5} − 2,18 : 0,2 = -\frac{2053}{190}$.

Do $ \frac{-91}{200}>-\frac{2053}{190}$.

=> $(\frac{9}{25}−2,18):(3\frac{4}{5})+0,2) > \frac{9}{25} : 3\frac{4}{5} − 2,18 : 0,2$.