\(a,=5\sqrt{5}-12\sqrt{5}+6\sqrt{5}-4\sqrt{5}\\ =\left(5-12+6-4\right)\sqrt{5}\\ =-5\sqrt{5}\)
\(b,=2.\dfrac{3\sqrt{3}}{2}-\dfrac{4\sqrt{3}}{3}-\dfrac{2}{5}.\dfrac{5\sqrt{3}}{4}\\ =3\sqrt{3}-\dfrac{4\sqrt{3}}{3}-\dfrac{\sqrt{3}}{2}\\ =\dfrac{7\sqrt{3}}{6}\)
\(c,=\sqrt{\left(\sqrt{3}+2\right)^2}+\sqrt{\left(5-\sqrt{3}\right)^2}\\ =\left|\sqrt{3}+2\right|+\left|5-\sqrt{3}\right|\\ =\sqrt{3}+2+5-\sqrt{5}\\ =7\)
\(d,=\dfrac{14\left(\sqrt{10}-\sqrt{3}\right)}{10-3}-2\sqrt{10}\\ =2\left(\sqrt{10}-\sqrt{3}\right)-2\sqrt{10}\\ =2\sqrt{10}-2\sqrt{3}-2\sqrt{10}\\ =-2\sqrt{3}\)
