If x +iy =(a+ib) whole raised to cube ...show that x/a+y/b=4(a square -b square)

people this is a sum from complex numbers....i cant understand a thing..pls help....that i is imaginary number

OK, it would help if you used mathematical notations:
Use ^ to denote exponents:
x^2 = x squared
x^3 = x cubed
etc...

x + iy = (a + ib)^3
x + iy = a³ + 3 a² * ib + 3 a * i²b² + i³b³
x + iy = a³ + 3a²b i − 3ab² − b³ i
x + iy = (a³ − 3ab²) + i (3a²b − b³)

x = a³ − 3ab²
y = 3a²b − b³

x/a + y/b = (a³ − 3ab²)/a + (3a²b − b³)/b
. . . . . . . = a² − 3b² + 3a² − b²
. . . . . . . = 4a² − 4b²
. . . . . . . = 4 (a² − b²)