17) (√42 - 2)² + 4√42

Решение:

1. \[ (\sqrt{42} - 2)^2 + 4\sqrt{42} = ((\sqrt{42})^2 - 2 \cdot 2 \cdot \sqrt{42} + 2^2) + 4\sqrt{42} \]
2. \[ = (42 - 4\sqrt{42} + 4) + 4\sqrt{42} \]
3. \[ = 42 + 4 - 4\sqrt{42} + 4\sqrt{42} = 46 \]

Ответ: 46