Cops - square times square root
Python 3, 44 bytes (cracked)
'**:(((paraboloid / rabid,mad,immoral))):**'
No rounding. Floating point accuracy.
MATL, 12 bytes (cracked by @tehtmi)
No rounding; uses floating point.
Intended solution (different from that found by @tehtmi):
:&+ % Create a matrix of size n × n, where n is implicit input
n % Number of elements. Gives n^2
10U % 10 squared. Gives 100
'P' % 'P' (ASCII code 80)
/ % Divide. Gives 1.25
^ % Power. Implicit display
Röda, 28 bytes (Cracked by @tehtmi)
Note the space at the beginning. No rounding, but it uses floating point numbers so precision is limited.