(-1)square 5 =5
11.91-4=11.87
18: (-2) =9
are these problem right.
I don't think so, it is hard to tell what your questions mean.
(-1)square 5 =5
are you multiplying -1 by the square of 5?
if so, then (-1)(5^2) = -25
11.91-4=11.87 ????
11.91-4= 7.91
18: (-2) =9 ??? is that supposed to be a division?
if so, then 18 ÷ (-2) = - 9