II 2) [tex]4\sqrt{2} -12\sqrt{2} + 15\sqrt{2} = 7\sqrt{2} [/tex]
II 4) [tex]\frac{2\sqrt{2}}{\sqrt{21}}.\frac{21\sqrt{2}}{-5}.\frac{-2}{3\sqrt{7}} = \frac{-8}{5}[/tex]
IV[tex]\frac{2\sqrt{3}-7}{5\sqrt{2}}=\frac{2\sqrt{6}-7\sqrt{2}}{10}}[/tex]
V 3x²-15+7=x²-9
2x²=-1 impossible
