a) \(\sqrt{7-2\sqrt{10}}+\sqrt{2}\)
\(=\sqrt{5}-\sqrt{2}+\sqrt{2}\)
\(=\sqrt{5}\)
b) \(\sqrt{4+\sqrt{7}}+\sqrt{4-\sqrt{7}}\)
\(=\dfrac{\sqrt{8+2\sqrt{7}}+\sqrt{8-2\sqrt{7}}}{\sqrt{2}}\)
\(=\dfrac{\sqrt{7}+1+\sqrt{7}-1}{\sqrt{2}}=\sqrt{14}\)
Rút gọn hả;-;
a)A= \(\sqrt{7-2\sqrt{10}}+\sqrt{2}\)
\(\sqrt{2}A=\sqrt{14-4\sqrt{10}}+2=\sqrt{\left(\sqrt{10}-2\right)^2}+2=\sqrt{10}-2+2=\sqrt{10}\)
\(A=\sqrt{5}\)
b) Rồi 4 hay 9 vậy ;-;
B=\(\sqrt{4+\sqrt{7}}+\sqrt{4-\sqrt{7}}\)
\(\sqrt{2}B=\sqrt{8+2\sqrt{7}}+\sqrt{8-2\sqrt{7}}=\sqrt{\left(\sqrt{7}+1\right)^2}+\sqrt{\left(\sqrt{7}-1\right)^2}=\sqrt{7}+1+\sqrt{7}-1=2\sqrt{7}\)\(B=\sqrt{14}\)