Bài 4: Rút gọn căn bậc 2 theo hằng đẳng thức
a> \(\sqrt{8+2\sqrt{15}}\)
b> \(\sqrt{23+4\sqrt{15}}\)
c> \(\sqrt{11+4\sqrt{6}}\)
d> \(\sqrt{14-6\sqrt{5}}\)
e> \(\sqrt{22-8\sqrt{6}}\)
f> \(\sqrt{16-6\sqrt{7}}\)
g> \(\sqrt{9-4\sqrt{2}}\)
h> \(\sqrt{13-4\sqrt{3}}\)
i> \(\sqrt{7-4\sqrt{3}}\)
j> \(\sqrt{21-8\sqrt{5}}\)
k> \(\sqrt{4-2\sqrt{3}}\)
p> \(\sqrt{5-2\sqrt{6}}\)
s>\(\sqrt{10-2\sqrt{21}}\)
x> \(\sqrt{28-10\sqrt{3}}\)
y> \(\sqrt{9-4\sqrt{5}}\)
a, \(\sqrt{8+2\sqrt{15}}=\left(\sqrt{5}\right)^2-2\sqrt{3}.\sqrt{5}-\left(\sqrt{3}\right)^2\)
\(=\sqrt{\left(\sqrt{5}-\sqrt{3}\right)^2}\)
\(=\sqrt{5}-\sqrt{3}\)
b,
