10 factorial divided by 9 factorial, that's 10. So n factorial divided by n minus 1 factorial, that's just equal to n. So this is equal to n times x to the n minus 1. So that's the derivative of x to the n. n times x to the n minus 1. So we just proved the derivative for any positive integer, x to the power n, where n is any positive integer. And we see later it actually works for all, actually, real numbers in the exponent. So I will see you in a future video. Oh, and another thing I wanted to point out is, I said that we had to know the binomial theorem.