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)

'Un&0P'/^:+1

No rounding; uses floating point.

Intended solution (different from that found by @tehtmi):

:&+n10U'P'/^

Explanation

:&+ % 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)

 (),.025^^cdfhnnnopprstuu{|}

Note the space at the beginning. No rounding, but it uses floating point numbers so precision is limited.