I suck at math, can you help me understand this?

Yes they do you retard, that's why I said it's IMPLICITLY STATED. Stating that i=/=-1 it's stating the obvious, unles you need to keep working with the original equation to solve for i. In this case if d is a real number then yes i is equal to any real number except for -1.

This is why I don't take online courses anymore. They just end up being a waste of time.

God damn to fucked up retarded mother fucker. Put down the bong and read your fucking text book

yeah it's sad to say but when anything becomes driven completely by profit motive its value is reduced usually. online college is not considered quality education even by those selling it. it's done purely for money and is even worse if there are stockholders in the mix

Different person, fuckface.

I agree, even the shittest class in person is better than an online class. You can at least ask your classmates and professors questions and help in real time.