\(a.x_1=5,4;x_2=1\\ b.x=\dfrac{-\left(1+\sqrt{2}\right)\pm\sqrt{27+10\sqrt{2}}}{4}\\ c.x_1=13,5;x_2=-1\\ d.x=\dfrac{-3+\sqrt{2}\pm\sqrt{11+6\sqrt{2}}}{6}\\ e.x=\dfrac{\sqrt{3}+\sqrt{5}\pm\sqrt{8-2\sqrt{15}}}{2}\\ f.x=\dfrac{2+\sqrt{3}\pm\sqrt{7-4\sqrt{3}}}{2}\)