a)\(3\sqrt{5}\left(\sqrt{45}+2\sqrt{125}-4\sqrt{80}\right)=3\sqrt{5}\left(3\sqrt{5}+10\sqrt{5}-16\sqrt{5}\right)=45+150-240=-45\)b) \(\sqrt{2+\sqrt{3}}\cdot\sqrt{2-\sqrt{3}}=\sqrt{\left(2+\sqrt{3}\right)\left(2-\sqrt{3}\right)}=\sqrt{4-3}=1\)
c) \(\sqrt{\left(4-\sqrt{15}\right)^2}+\sqrt{\left(3-\sqrt{15}\right)^2}=\left|4-\sqrt{15}\right|+\left|3-\sqrt{15}\right|=4-\sqrt{15}+\sqrt{15}-3=1\)
d) \(\sqrt{\dfrac{6\sqrt{3}-8}{2\sqrt{3}+1}}=\sqrt{\dfrac{\left(6\sqrt{3}-8\right)\left(2\sqrt{3}-1\right)}{11}}=\sqrt{\dfrac{36-6\sqrt{3}-16\sqrt{3}+8}{11}}=\sqrt{\dfrac{44-22\sqrt{3}}{11}}=\sqrt{4-2\sqrt{3}}=\sqrt{\left(\sqrt{3}-1\right)^2}=\sqrt{3}-1\)
Tick nha bạn 😘
