Răspuns:
19.
a)
[tex]4 \sqrt{3} (10 \sqrt{3} - 3\sqrt{3} + 6 \sqrt{3} ) - 2 \sqrt{3} \times 4 \sqrt{3} = 156 - 24 = 132[/tex]
20.
a)
[tex] \sqrt{5} (3 + \sqrt{15} ) - 5 \sqrt{3} + 2 \sqrt{5} = 3 \sqrt{5} + 5 \sqrt{3} - 5 \sqrt{3} + 2 \sqrt{5} = 5 \sqrt{5} [/tex]
