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← JEE Main 2014 · 11 Apr · Shift 1
MathematicsSingle correct+4 / -1Question 62 of 90

JEE Main 2014 · 11 Apr · Shift 1, Mathematics question 62

If z1z_1, z2z_2 and z3z_3, z4z_4 are 2 pairs of complex conjugate numbers, then arg⁡(z1z4)+arg⁡(z2z3)\arg\left(\dfrac{z_1}{z_4}\right)+\arg\left(\dfrac{z_2}{z_3}\right) equals :

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Answer and worked solution

Official answer: A

With z2=zˉ1z_2=\bar z_1 and z4=zˉ3z_4=\bar z_3:
arg⁡z1z4+arg⁡z2z3=arg⁡z1zˉ1zˉ3z3=arg⁡∣z1∣2∣z3∣2=0.\arg\frac{z_1}{z_4}+\arg\frac{z_2}{z_3}=\arg\frac{z_1\bar z_1}{\bar z_3z_3}=\arg\frac{|z_1|^2}{|z_3|^2}=0.