Răspuns:
1) C 2) A 4) C
Explicație pas cu pas:
1) [tex](\sqrt{3}+2)^{2} + (\sqrt{3}-2)^{2}-(2\sqrt{3}+1)^{2}[/tex]
[tex](a ±b)^{2}=a^{2}±2ab+b^{2}[/tex]
[tex]3+4\sqrt{3}+4+3-4\sqrt{3}+4-(12+4\sqrt{3}+1)[/tex]
[tex]3+4+3+4-(13+3\sqrt{3})[/tex]
[tex]3+4+3+4-13-4\sqrt{3}=1-4\sqrt{3}[/tex]
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2) (-324) ÷ (-18) + (-3)² - 4²
18 + 9 - 16 = 11
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4) 4 robinete .......... 9 ore
6 robinete .......... x ore
[tex]x=\frac{9*4}{6}[/tex]
x = 3 × 2
x = 6 ore
