Find the modulus of $(1 + 2 i) (1 + i)$

\sqrt{10}

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10

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5

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6

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Solution

The correct option is A $\sqrt{10}$
$| z_{1} z_{2} | = | z_{1} | | z_{2} |$

Hence $| (1 + 2 i) (1 + i) | = | 1 + 2 i | | 1 + i | = \sqrt{5} \times \sqrt{2} = \sqrt{10}$

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