/usr/lib/x86_64-linux-gnu/libMathCore.so is in libroot-math-mathcore-dev 5.34.30-0ubuntu8.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/root5.34/libMathCore.so
/usr/lib/x86_64-linux-gnu/root5.34/libMathCore.so