Private Sub CommandButton1_Click()
Dim x As Single, y As Single, z As Single, f As Single
If IsNumeric(TextBox1.Text) And IsNumeric(TextBox3.Text) And IsNumeric(TextBox5.Text) Then
x = TextBox1.Text
y = TextBox3.Text
z = TextBox5.Text
f = 0
If x > 0 Then f = ln ^ 2 * (x + 2)
If y > 0 Then f = y / 2 + Sin(z)
If 1 < z < 2 Then f = y / 2 + Sin(z)
TextBox7.Text = f
Else
MsgBox ("&#207;&#238;&#226;&#242;&#238;&#240;&#232;&#242;&#229; &#226;&#226;&#238;&#228; !!!!!!!!!!")
TextBox1.Text = ""
TextBox3.Text = ""
TextBox5.Text = ""
End If
End Sub