[tex]a) \: mg = \sqrt{12 \times 3} = \sqrt{36} = \sqrt{ {36}^{2} } = \\ = 36 \\ b) \: mg = \sqrt{8 \times 2} = \sqrt{16} = \sqrt{ {8}^{2} } = 8 \\ c) \: mg = \sqrt{18 \times 8} = \sqrt{144} = \sqrt{ {12}^{2} } = \\ = 12 \\ [/tex]
[tex]d) \: mg = \sqrt{16 \times 5} = \sqrt{ 80 } = 4 \sqrt{5} \\ e) \: mg = \sqrt{ \frac{7}{2} \times 7} = \sqrt{ \frac{49}{2} } = \frac{ \sqrt{49} }{ \sqrt{2} } = \\ \frac{ \sqrt{ {7}^{2} } }{ \sqrt{2} } = \frac{7}{ \sqrt{2} } = \frac{7 \sqrt{2} }{2} [/tex]
Sper ca te-am ajutat =)