[tex] - 0.2 \sqrt{3} = - \sqrt{ { 0.2}^{2} \times 3 } = -\sqrt{0.04 \times 3} = - \sqrt{0.12} [/tex]
[tex] - 1.(3) \sqrt{21} = -\frac{12}{9} \sqrt{21} = -\sqrt{( \frac{4}{3}) ^{2} \times 21 } = -\sqrt{ \frac{16}{9} \times 21 } = -\sqrt{ \frac{336}{9} } = -\sqrt{ \frac{112}{3} } [/tex]
[tex] - 0.1 \sqrt{3} = - \sqrt{ {0.1}^{2} \times 3} = -\sqrt{0.01 \times 3} = - \sqrt{0.03} [/tex]
