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