双显卡下安装ubuntu18.04

重点参考链接：
https://www.cnblogs.com/tanrong/p/9166595.html
https://blog.csdn.net/baidu_37071386/article/details/78882062
https://blog.csdn.net/bush_nj/article/details/80850937
https://linuxconfig.org/how-to-install-the-nvidia-drivers-on-ubuntu-18-04-bionic-beaver-linux
https://blog.csdn.net/qq_37935670/article/details/80377196