Răspuns:
a)
[tex]( \sqrt{2} + \sqrt{8} )^{2} = ( \sqrt{2} + 2 \sqrt{2} )^{2} = (3 \sqrt{2} )^{2} = 18[/tex]
b)
[tex]2 \sqrt{500} = 2 \times 10 \sqrt{5} = 20 \sqrt{5} [/tex]
[tex] \sqrt{3} \times \sqrt{1500} = \sqrt{4500} = \sqrt{ {3}^{2} \times 5 \times 100} = 10 \times 3 \sqrt{5} = 30 \sqrt{5} [/tex]
[tex](20 \sqrt{5} - 30 \sqrt{5} )^{2} = ( - 10 \sqrt{5} )^{2} = 500[/tex]
c)
[tex]4 \sqrt{20} = 4 \sqrt{ {2}^{2} \times 5 } = 8 \sqrt{5} [/tex]
[tex]3 \sqrt{45} = 9 \sqrt{5} [/tex]
[tex](8 \sqrt{5} - 9 \sqrt{5} )^{2} = ( - \sqrt{5})^{2} = 5[/tex]
