解一个关于x的4次方程

ysr

这个结果也对：输入:  a=1,  b=2,  c=-3,  d=4，e=5;  输出结果:    x1,2=-1.9556023509+ -1.2268754722,  x3,4=0.9556023509+ -1.1148003552i

因为其中的解2次方程的可调用程序不同，代码如下：
Public Function jie2cifc(a2 As String, b2 As String, C2 As String, sd As String) As String '2次方程
Dim d, Y
d = mbc2(Trim(b2), Trim(b2), Val(sd))
D1 = mpc2(Trim(d), mbc2(4 & String(sd, "0"), mbc2(Trim(a2), Trim(C2), Val(sd)), Val(sd)))
d3 = qdfh(Trim(D1))
D2 = mbbc2(Trim(d3), Val(sd))
Y = mcc2(Trim(b2), mbc2(2 & String(sd, "0"), Trim(a2), Val(sd)), Val(sd))
sf = fhys(Trim(Y))
sf = Val(-1 * sf)
Y = tjfh(qdfh(Trim(Y)), Val(sf))
Y = shuchujg(Trim(Y), Val(sd))
If mbjc2(Trim(D1), 0) >= 0 Then
d3 = mcc2(Trim(D2), mbc2(2 & String(sd, "0"), Trim(a2), Val(sd)), Val(sd))
d3 = shuchujg(Trim(d3), Val(sd))
Else
d3 = mcc2(Trim(D2), mbc2(2 & String(sd, "0"), Trim(a2), Val(sd)), Val(sd))
d3 = shuchujg(Trim(d3), Val(sd)) & "i"
End If
jie2cifc = Y & "+ -" & d3
End Function