Question

how comes -2^2=-4 but (-2)^2=4?

Answer 1

Because if you multiply -2 two times, you will get 4.
But in the first case, it is -(2 * 2)
= -4

Answer 2

The position of the negative sign is the difference between the two.

Answer 3

This is operator precedence, the brackets force the evaluation as a square of -2
whereas in the other, the exponent is first and the minus after.