theorem
for
x0,
x1,
x2,
x3,
x4,
k being
Real for
f being
Function of
REAL,
REAL st ( for
x being
Real holds
f . x = k / x ) &
x0 <> 0 &
x1 <> 0 &
x2 <> 0 &
x3 <> 0 &
x4 <> 0 &
x0,
x1,
x2,
x3,
x4 are_mutually_distinct holds
[!f,x0,x1,x2,x3,x4!] = k / ((((x0 * x1) * x2) * x3) * x4)