\[ \sqrt{0.64} - \sqrt{0.04} = 0.8 - 0.2 = 0.6 \]
\[ 3 \cdot \sqrt{0.16} = 3 \cdot 0.4 = 1.2 \]
\[ \sqrt{900} \cdot \sqrt{100} = 30 \cdot 10 = 300 \]
Ответ: а) 0.6; б) 1.2; в) 300