a47.go

package main

import (
    "fmt"
    "math/cmplx"
)

func Cbrt(x complex128) complex128 {
    z := complex(1, 0)
    for i := 0; i < 10; i++ {
        z = z - (z*z*z - x)/(3*z*z)
    }
    return z
}

func main() {
    fmt.Println(Cbrt(2))
    fmt.Println(cmplx.Pow(Cbrt(2), 3))
}