Question

Va rog Ajutați ma . Măcar primele trei

Answer 1

[tex]a). \sqrt{6-4 \sqrt{2} }+ \sqrt{6+4 \sqrt{2} } = \sqrt{(2- \sqrt{2})^{2} } + \sqrt{(2+ \sqrt{2})^2 } = \\ \\ =2- \sqrt{2} +2+ \sqrt{2} =4 \\ \\ b). \sqrt{14-6 \sqrt{5} }+ \sqrt{14+6 \sqrt{5} } = \sqrt{(3- \sqrt{5} )^2} + \sqrt{(3+ \sqrt{5})^2 } = \\ \\ =3- \sqrt{5} +3+ \sqrt{5} =6 \\ \\ c) \sqrt{12-6 \sqrt{3} } + \sqrt{12+6 \sqrt{3}} = \sqrt{(3- \sqrt{3} )^2} + \sqrt{(3+ \sqrt{3})^2 } = \\ \\ =3- \sqrt{3} +3+ \sqrt{3} =6 \\ \\[/tex]

Answer 2

d) 21-8√5=16-8√5+5=4²-2×4√5+(√5)²=(4-√5)²
21+8√5=16+8√5+5=4²+2×4√5+(√5)²=(4+√5)²
√21-8√5=√(4-√5)²=l4-√5l=4-√5
√21+8√5=√(4+√5)²=l4+√5l=4+√5
4-√5+4+√5=4+4=8