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The modulus of the complex number |(3 + 4i)/(1 − 2i)| is

1. 5
2. √5
3. 1/√5
4. 1/5

Correct answer: √5

Solution

|3+4i|=5 and |1-2i|=sqrt(5). The modulus of the quotient is 5/sqrt(5)=sqrt(5). The stored 1/sqrt(5) inverts the ratio.

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