[tex]\it a)\ \ \sqrt{12}+\sqrt{108}=\sqrt{4\cdot3} +\sqrt{36\cdot3} = 2\sqrt3+6\sqrt3 =8\sqrt3\\ \\ \\ g)\ \ \sqrt{98} -\sqrt{128}=\sqrt{49\cdot2}+\sqrt{64\cdot2} = 7\sqrt2+8\sqrt2=15\sqrt2[/tex]
