You seem to be close. How did the '5' get into the numerator?
I know that r^6 changes to 6r^5, r changes to 1, and the -1 is eliminated because it turns to 0.. but i'm kind of confused what to do with the - 2/5squareroot of r
Do I have to use the quotient rule? Or is it just bringing 5(r)^1/2 to the numerator, changing it to r^-1/2 and multiplying it by -2.