`b)`

`\sqrt{98} - 2 \sqrt{72} + 0,5 \sqrt{32}`

` = 7 \sqrt{2} - 2 . 6 \sqrt{2} + 0,5 . 4 \sqrt{2}`

` = 7 \sqrt{2} - 12 \sqrt{2} + 2 \sqrt{2}`

` = (7 - 12+2) \sqrt{2}`

` = -3 \sqrt{2}`

`c)`

`3 \sqrt{18} - \sqrt{50} - 3/2 \sqrt{8}`

` = 3 . 3 \sqrt{2} - 5 \sqrt{2} - 3/2 . 2 \sqrt{2}`

` = 9 \sqrt{2} - 5 \sqrt{2} - 3 \sqrt{2}`

` = (9-5-3)\sqrt{2}`

` = \sqrt{2}`

`d)`

`\sqrt{12} - 5 \sqrt{3} - \sqrt{27}`

` = 2 \sqrt{3} - 5 \sqrt{3} - 3 \sqrt{3}`

` = (2-5-3)\sqrt{3}`

`= -6 \sqrt{3}`

`e)`

`\sqrt{121} - \sqrt{25} . \sqrt{4}`

` = 11 - 5 . 2`

` = 11-10`

` = 1`

`f)`

`\sqrt{18} - 2 \sqrt{50} + 3 \sqrt{8}`

` = 3 \sqrt{2} - 2 . 5 \sqrt{2} + 3 . 2 \sqrt{2}`

`= 3 \sqrt{2} - 10 \sqrt{2} + 6 \sqrt{2}`

` = - \sqrt{2}`

`g)`

`\sqrt{2021} - \sqrt{ (\sqrt{2020} - \sqrt{2021})^2 }`

` = \sqrt{2021} - |\sqrt{2020} - \sqrt{2021}|`

`= \sqrt{2021} + ( \sqrt{2020} - \sqrt{2021})`

` = \sqrt{2021} + \sqrt{2020} - \sqrt{2021}`

` = \sqrt{2020}`

b) $\sqrt[]{98}-2\sqrt[]{72}+0,5\sqrt[]{32}$

$=\sqrt[]{2.49}-2\sqrt[]{2.36}+0,5\sqrt[]{2.16}$

$=7\sqrt[]{2}-2.6\sqrt[]{2}+0,5.4\sqrt[]{2}$

$=7\sqrt[]{2}-12\sqrt[]{2}+2\sqrt[]{2}$

$=-3\sqrt[]{2}$

c) $3\sqrt[]{18}-\sqrt[]{50}-1,5\sqrt[]{8}$

$=3\sqrt[]{2.9}-\sqrt[]{2.25}-1,5\sqrt[]{2.4}$

$=3.3\sqrt[]{2}-5\sqrt[]{2}-1,5.2\sqrt[]{2}$

$=9\sqrt[]{2}-5\sqrt[]{2}-3\sqrt[]{2}$

$=\sqrt[]{2}$

d) $\sqrt[]{12}-5\sqrt[]{3}-\sqrt[]{27}$

$=\sqrt[]{3.4}-5\sqrt[]{3}-\sqrt[]{3.9}$

$=2\sqrt[]{3}-5\sqrt[]{3}-3\sqrt[]{3}$

$=-6\sqrt[]{3}$

e) $\sqrt[]{121}-\sqrt[]{25}.\sqrt[]{4}$

$=11-5.2=1$

f) $\sqrt[]{18}-2\sqrt[]{50}+3\sqrt[]{8}$

$=\sqrt[]{2.9}-2\sqrt[]{2.25}+3\sqrt[]{2.4}$

$=3\sqrt[]{2}-2.5\sqrt[]{2}+3.2\sqrt[]{2}$

$=3\sqrt[]{2}-10\sqrt[]{2}+6\sqrt[]{2}$

$=-\sqrt[]{2}$

g) $\sqrt[]{2021}-\sqrt[]{(\sqrt[]{2020}-\sqrt[]{2021})^2}$

$=\sqrt[]{2021}-|\sqrt[]{2020}-\sqrt[]{2021}|$

$=\sqrt[]{2021}-(\sqrt[]{2021}-\sqrt[]{2020})$

$=\sqrt[]{2020}$