Math Chapter Wise Complex Number, De Moivre's Theorem And Nth Root Of Unity English MCQ TGT 2009 Q.If (x+iy)1/3 = a + ib then the value of x y a b + + will be: A4(a2 + b2) B4(a2 –b2) C4(b2 – a2) DNone of these Show answer Correct answer: 4(a2 –b2)