Đáp án:
Bài 1:
b) $4$
$\sqrt{17-12\sqrt{2}}+\sqrt{9+4\sqrt{2}}$
$=\sqrt{17-6\sqrt{8}}+\sqrt{9+2\sqrt{8}}$
$=\sqrt{8-2.\sqrt{8}.3+9}+\sqrt{8+2\sqrt{8}+1}$
$=\sqrt{(\sqrt{8}-3)^2}+\sqrt{(\sqrt{8}+1)^2}$
$=|\sqrt{8}-3|+|\sqrt{8}+1|$
$=3-\sqrt{8}+\sqrt{8}+1$
$=4$
c) $2\sqrt{2}$
$\sqrt{6-4\sqrt{2}}+\sqrt{22-12\sqrt{2}}$
$=\sqrt{6-4\sqrt{2}}+\sqrt{22-4\sqrt{18}}$
$=\sqrt{4-2.2.\sqrt{2}+2}+\sqrt{18-2.\sqrt{18}.2+4}$
$=\sqrt{(2-\sqrt{2})^2}+\sqrt{(\sqrt{18}-2)^2}$
$=|2-\sqrt{2}|+|\sqrt{18}-2|$
$=2-\sqrt{2}+\sqrt{18}-2$
$=\sqrt{18}-\sqrt{2}$
$=3\sqrt{2}-\sqrt{2}$
$=2\sqrt{2}$
