Question

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Answer 1

$\sqrt{18} = \sqrt{9 \times 2} = \sqrt{3 {}^{2} \times 2 } = 3 \sqrt{2}$

$\sqrt{2} + 2x = \sqrt{18} \\ \\ \sqrt{2} + 2x = 3 \sqrt{2} \\ 2x = 3 \sqrt{2} - \sqrt{2} \\ 2x = 2 \sqrt{2} \\ x = 2 \sqrt{2} \div 2 \\ x = \sqrt{2}$