Упростите выражение: 7√2 - 3√8 + 4√18; (√90 - √40) * √10; (3√5 - 2)²;...

Решите задачу:

$7 \sqrt{2} - 3 \sqrt{4 \times 2} + 4 \sqrt{9 \times 2} = \\ 7 \sqrt{2} - 3 \times 2 \sqrt{3} + 4 \times 3 \sqrt{2} = \\ 7 \sqrt{2} - 6 \sqrt{2} + 12 \sqrt{2} = 13 \sqrt{2 } \\ \\ ( \sqrt{90} - \sqrt{40} ) \times \sqrt{10} = \\ \sqrt{900} - \sqrt{400} = 30 - 20 = 10 \\ \\ {(3 \sqrt{5} - 2) }^{2} = \\ {(3 \sqrt{5}) }^{2} - 2 \times 3 \sqrt{5} \times 2 + {2}^{2} = \\ 45 - 6 \sqrt{5} + 4 = 49 - 6 \sqrt{5} \\ \\ (7 \sqrt{2} - 3 \sqrt{3} )(7 \sqrt{2} + 3 \sqrt{3} ) = \\ {(7 \sqrt{2} )}^{2} - {(3 \sqrt{3} )}^{2} = \\ 98 - 27 = 71$