Răspuns:
21. a)
[tex]2 \sqrt{3} + 3 \sqrt{2} - 2 \sqrt{3} + 5 \sqrt{2} = 8 \sqrt{2} [/tex]
c)
[tex]5 \sqrt{3} + 3 \sqrt{2} - 4 \sqrt{3} - 3 \sqrt{2} - \sqrt{3} = \sqrt{3} [/tex]
e)
[tex]18 \sqrt{5} - 3 \sqrt{7} + 10 \sqrt{7} - 9 \sqrt{5} + 1 = 9 \sqrt{5} + 7 \sqrt{7} + 1[/tex]
