If |z1| = 1, |z2| = 2, |z3| = 3 and |9z1z2 + 4z1z3 + z2z3 | = 12, then the value of |z1 + z2 + z3| is
A
56
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B
60
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C
2
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D
64
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Solution
The correct option is C2 Given |z1|=1,|z2|=2,|z3|=3 and |9z1z2+4z1z3+z2z3|=12 |9z1z2+4z1z3+z2z3|=12 ⇒|z1||z2||z3|∣∣∣9z3+4z2+1z1∣∣∣=12 ⇒6∣∣
∣∣9¯z3|z3|2+4¯z2|z2|2+¯z1|z1|2∣∣
∣∣=12 ⇒6|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯z1+z2+z3|=12 ⇒6|z1+z2+z3|=12 ∴|z1+z2+z3|=2