Here is an excellent instruction video. I had some problems; so I did a fresh install of 18.04 and never updated my video driver. I kept the Nouveax driver up until I added the PPA mentioned in this video. Now Tensorflow is running fine on my crummy old Geforce GTX 760. BTW, I installed Anaconda 3.6 first. https://www.youtube.com/watch?v=vxjbL5iN1XY&lc=z23zfhcjlzufyts25acdp4312z3plnshryrb25y5clhw03c010c.1526067048057471
It makes me wonder if there isn't something seriously wrong for Ubuntu with Nvidia's proprietary driver.