Ahh, never mind, it's a bug in the editing...TeX doesn't calculate anything; it's just a type setting program. All it does is let you type up nice papers (though it is very useful for writing up your math homework in college if you're taking some advanced courses).
I first wrote my whole math, but then it looked all crazy, and it looked like it were calculating every part I wrote, so I edited it to only "-9^-1" and it looked like it were calculating the whole thing, until I refreshed the website...
And btw, I was taught that ^-1 means squareroot.
81^-2 = 3 because, 3^2 = 81
Here's my math:
And if ^-1 doesn't mean sqrt then: