[tex]\dfrac{1}{4}\cdot\sqrt{8}=\dfrac{1}{4}\cdot\sqrt{4\cdot2} = \dfrac{1}{4}\cdot\sqrt{4}\cdot\sqrt{2} = \dfrac{1}{4}\cdot2\cdot\sqrt{2} =\dfrac{1}{2}\sqrt{2}[/tex]
[tex]\huge{2\cdot7^{23}-4\cdot7^{23}+9\cdot7^{23} =7^{23}(2-4+9) = 7^{23}\cdot7}=7^{23+1} = 7^{24}[/tex]
