Đáp án:
$a)2(\sqrt{3}-1)^2\\ b)2(\sqrt{5}-1)^2\\ c)2(\sqrt{7}-1)^2\\ d)(\sqrt{3}+\sqrt{2})^2\\ e)(\sqrt{5}+\sqrt{3})^2.$
Giải thích các bước giải:
$a)8-4\sqrt{3}=2(4-2\sqrt{3})=2(3-2\sqrt{3}+1)=2(\sqrt{3}-1)^2\\ b)12-4\sqrt{5}=2(6-2\sqrt{5})=2(5-2\sqrt{5}+1)=2(\sqrt{5}-1)^2\\ c)16-4\sqrt{7}=2(8-2\sqrt{7})=2(7-2\sqrt{7}+1)=2(\sqrt{7}-1)^2\\ d)5-2\sqrt{6}=3-2.\sqrt{3}.\sqrt{2}.2=(\sqrt{3}+\sqrt{2})^2\\ e)8+2\sqrt{15}=5+2\sqrt{5}.\sqrt{3}+3=(\sqrt{5}+\sqrt{3})^2.$
