Question

rút gọn căn thức

Answer 1

\(B=\dfrac{\sqrt{8+2\sqrt{15}}}{\sqrt{12}+\sqrt{20}}=\dfrac{\sqrt{\left(\sqrt{3}+\sqrt{5}\right)^2}}{\sqrt{12}+\sqrt{20}}\\ B=\dfrac{\sqrt{3}+\sqrt{5}}{\sqrt{12}+\sqrt{20}}=\dfrac{\left(\sqrt{3}+\sqrt{5}\right)\left(\sqrt{20}-\sqrt{12}\right)}{8}\\ B=\dfrac{2\sqrt{15}-6+10-2\sqrt{15}}{8}=\dfrac{4}{8}=\dfrac{1}{2}\)

Tick nha 😘

Answer 2

\(B=\dfrac{\sqrt{8+2\sqrt{15}}}{\sqrt{12}+\sqrt{20}}=\dfrac{\sqrt{5}+\sqrt{3}}{2\left(\sqrt{5}+\sqrt{3}\right)}=\dfrac{1}{2}\)