How does -2 squared = 2i?
No -2^2 does not equal 2i, the square root of -2 is 2i. This if you are not in algebra 2 yet is because they made up a number that is equal to the square root of -1=i. -2 squared however is just positive 2.
If it is:
(-2)^2 = 4
-(2)^2 = -4