Question

A)[9·(-8pe 15)°-7]-²
B)2√20 - 3√45-√2(3√18-2)

Answer 1

$a) \\ \\ [9 \times ( - \frac{8}{15}) ^{0} - 7] ^{ - 2} = \\ \\ {( - \frac{8}{15}) }^{0} = 1 \\ \\ 9 \times 1 = 9 \\ \\ 9 - 7 = 2 \\ \\ {2}^{( - 2)} = 0,25 = \frac{1}{4}$

$b) \\ \\ 2 \sqrt{20} - 3 \sqrt{45} - \sqrt{2}(3 \sqrt{18} - 2) = \\ \\ 2 \times 2 \sqrt{5} - 3 \times 3 \sqrt{5} - \sqrt{2}(3 \times 3 \sqrt{2} - 2) = \\ \\ 4 \sqrt{5} - 9 \sqrt{5} - \sqrt{2}(9 \sqrt{2} - 2) = \\ \\ (4 \sqrt{5} - 9 \sqrt{5}) - \sqrt{2}(9 \sqrt{2} - 2) = \\ \\ - 5 \sqrt{5} - 18 + 2 \sqrt{2}$