[tex]x=\sqrt{2} +\sqrt{8} =\sqrt{2} +2\sqrt{2} =3\sqrt{2} \\x^2=(3\sqrt{2} )^2=3^2\sqrt{2^2} =9*2=18[/tex]
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[tex]x=2\sqrt{500} -\sqrt{3} *\sqrt{1500} =2*10\sqrt{5} -\sqrt{4500} =\\20\sqrt{5} -30\sqrt{5} =-10\sqrt{5} \\x^2=(-10\sqrt{5} )^2=10^2\sqrt{5^2} =100*5=500[/tex]
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[tex]x=4\sqrt{20} -3\sqrt{45} =4*2\sqrt{5} -3*3\sqrt{5} =\\8\sqrt{5} -9\sqrt{5} =-\sqrt{5} \\x^2=(-\sqrt{5})^2 =\sqrt{25} =5[/tex]
