Assuming you are using cuda 9. In Ubuntu I put these exports in my .profile. If your .profile is empty then this is not the place to put it. You will have to figure that out yourself. This is in the cuda documentation. You will want to leave out the numbers at the beginning.
sudo nano $HOME/.profile
export PATH=/usr/local/cuda-9.0/bin${PATH:+:${PATH}}
export LD_LIBRARY_PATH=/usr/local/cuda-9.0/lib64${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}
It might also be due to some 3rd party packages. In the cuda documentation it says to get these if you want to use the samples.
sudo apt-get install g++ freeglut3-dev build-essential libx11-dev libxmu-dev libxi-dev libglu1-mesa libglu1-mesa-dev
I also did a quick google search and saw on the third link something about “How To Install and Use FreeImage” it gave a library. So if the other things didn’t work try using the packages below.
sudo apt-get install libfreeimage3 libfreeimage-dev
If that doesn’t work use the Ubuntu that is supported with your cuda and cudnn version and do the things I put above. You probably don’t need to do the last one, though.