Q16 of 153 Page 14

Mark the Correct alternative in the following:

If (x + iy)1/3 = a + ib, then


(x + iy)1/3 = a + ib

x + iy = (a + ib)3


= a3 + (ib)3 + 3a2(ib) + 3a(ib)2


= a3 – ib3 + i3a2b – 3ab2


= (a3 – 3ab2) + i(3a2b – b3)


x = a3 – 3ab2 and y = 3a2b – b3



= a2 – 3b2 + 3a2 – b2


= 4(a2 – b2)

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