private void button_square_root_Click(object sender, EventArgs e)
{
if (chuoi1 != null || chuoi2 != null)
{
if (!kiemtra)
{
chuoi1 = TinhToan.canbac(float.Parse(chuoi1)).ToString();
}
else
{
chuoi2 = TinhToan.canbac(float.Parse(chuoi2)).ToString();
}
hienthi();
}
}
