90. Найдите значение выражения: 1) √81⋅16; 2) √0.09⋅25; 3) √0,01⋅0,04⋅121; 4) √30¹/₄⋅49/₃₆; 5) √6⁴⋅4²; 6) √(-2)⁶⋅0.3⁴⋅(-4)².

1) $$ \sqrt{81 \cdot 16} = \sqrt{81} \cdot \sqrt{16} = 9 \cdot 4 = 36 $$

2) $$ \sqrt{0.09 \cdot 25} = \sqrt{0.09} \cdot \sqrt{25} = 0.3 \cdot 5 = 1.5 $$

3) $$ \sqrt{0.01 \cdot 0.04 \cdot 121} = \sqrt{0.01} \cdot \sqrt{0.04} \cdot \sqrt{121} = 0.1 \cdot 0.2 \cdot 11 = 0.22 $$

4) $$ \sqrt{30 \frac{1}{4} \cdot \frac{49}{36}} = \sqrt{\frac{121}{4} \cdot \frac{49}{36}} = \frac{11}{2} \cdot \frac{7}{6} = \frac{77}{12} = 6 \frac{5}{12} $$

5) $$ \sqrt{6^4 \cdot 4^2} = 6^2 \cdot 4 = 36 \cdot 4 = 144 $$

6) $$ \sqrt{(-2)^6 \cdot 0.3^4 \cdot (-4)^2} = \sqrt{2^6 \cdot 0.3^4 \cdot 4^2} = 2^3 \cdot 0.3^2 \cdot 4 = 8 \cdot 0.09 \cdot 4 = 2.88 $$