If f(x) = 9x10 tan−1x, find f '(x). 90x9tan−1x + 9x10 1 over the quantity 1 plus x squared
90x9tan−1x + 9x10tan−2x
90x9tan−1x − 9x10 1 over the square root of the quantity 1 minus x squared
90x9tan−1x + 9x10 1 over the square root of the quantity 1 minus x squared
those are my choices

If they nenenenenenene

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.