1.
    Sub Main()
        Dim n As Integer
        n = 10
        Dim a(n) As Integer
        For i = 1 To n
            Console.Write("{0}-е число: ", i)
            a(i) = Int32.Parse(Console.ReadLine())
        Next i
        Console.WriteLine("Исходный массив:")
        For i = 1 To n
            Console.Write("{0} ", a(i))
        Next i
        Console.WriteLine()
        For i = 1 To n
            a(i) = -a(i)
        Next i
        Console.WriteLine("Измененный массив:")
        For i = 1 To n
            Console.Write("{0} ", a(i))
        Next i
        Console.ReadKey()
    End Sub
2.
        Dim n As Integer
        n = 10
        Dim a(n) As Integer
        For i = 1 To n
            Console.Write("{0}-е число: ", i)
            a(i) = Int32.Parse(Console.ReadLine())
        Next i
        Console.WriteLine("Исходный массив:")
        For i = 1 To n
            Console.Write("{0} ", a(i))
        Next i
        Console.WriteLine()
        For i = 1 To n
            If a(i) < 0 Then a(i) = a(i) * a(i)
        Next i
        Console.WriteLine("Измененный массив:")
        For i = 1 To n
            Console.Write("{0} ", a(i))
        Next i
        Console.ReadKey()
    End Sub