tính
\(\sqrt{97,5^2-2,5^2+15^2-85^2}\)
Thu gọn B= \(21\left(\sqrt{2+\sqrt{3}}+\sqrt{3-\sqrt{5}}\right)^2-6\left(\sqrt{2-\sqrt{3}}+\sqrt{3+\sqrt{5}}\right)^2-15\sqrt{5}\)
Thu gọn A= \(\left(2-\sqrt{3}\right)\sqrt{26+15\sqrt{3}}-\left(2+\sqrt{3}\right)\sqrt{26-15\sqrt{3}}\)
rút gọn B
B=\(\sqrt{8+2\sqrt{15}-2\sqrt{5}-2\sqrt{3}}\)-\(\sqrt{8-2\sqrt{15}-2\sqrt{5}+2\sqrt{3}}\)
chứng minh \(\sqrt{8-2\sqrt{15}-\sqrt{8+2\sqrt{15}}}=-2\sqrt{3}\)
rút gọn
\(\dfrac{2\sqrt{15}-2\sqrt{10}+\sqrt{6}-3}{2\sqrt{15}-2\sqrt{10}-\sqrt{3}+\sqrt{6}}\)
chứng minh
\(\sqrt{8-2\sqrt{15}}-\sqrt{8+2\sqrt{15}}=-2\sqrt{3}\)
Chứng minh
\(\left(\sqrt{4}-\sqrt{3}\right)^2=\sqrt{49}-\sqrt{48}\)
\(2\sqrt{2}\left(2-3\sqrt{3}\right)+\left(1-2\sqrt{2}\right)^2+6\sqrt{6}=9\)
\(\sqrt{8-2\sqrt{15}-\sqrt{8+2\sqrt{15}}}=-2\sqrt{3}\)
Tính: A = \(21\left(\sqrt{2+\sqrt{3}}+\sqrt{3-\sqrt{5}}\right)^2-6\left(\sqrt{2-\sqrt{3}}+\sqrt{3+\sqrt{5}}\right)^2-15\sqrt{15}\)
* Giải phương trình
a. \(\sqrt{45x}-2\sqrt{20x}+2\sqrt{80x}=21\)
b. \(\sqrt{x^2-10x+25}=4\)
* Chứng minh đẳng thức
\(\left(4+\sqrt{15}\right)\left(\sqrt{10}-\sqrt{6}\right)\sqrt{4-\sqrt{15}}=2\)