package main

import (
    "fmt"
    "math/cmplx"
)

func main() {
    z := complex(1, 2)
    fmt.Printf("The square root of %v is %v.", z, cmplx.Sqrt(z))
}

The square root of (1+2i) is (1.272019649514069+0.7861513777574233i).

package main

import (
    "fmt"
    "math/cmplx"
)

func main() {
    z := complex(5, -10)
    fmt.Printf("The square root of %v is %v.", z, cmplx.Sqrt(z))
}

The square root of (5-10i) is (3.1637929175230655-1.0522365423504464i).

package main

import (
    "fmt"
    "math/cmplx"
)

func main() {
    z := complex(-3, 4)
    fmt.Printf("The square root of %v is %v.", z, cmplx.Sqrt(z))
}

The square root of (-3+4i) is (1+2i).

package main

import (
    "fmt"
    "math/cmplx"
)

func main() {
    // 求解方程x^2 + 4x + 3 = 0的根
    a := 1.0
    b := 4.0
    c := 3.0

    // 计算判别式
    d := cmplx.Sqrt(complex(b*b-4*a*c, 0))

    // 计算分子
    root1 := (-b + d) / (2 * a)
    root2 := (-b - d) / (2 * a)

    fmt.Printf("The roots of the equation %gx^2 + %gx + %g are %v and %v.", a, b, c, root1, root2)
}

The roots of the equation 1x^2 + 4x + 3 are (-1+0i) and (-3+0i).