I don't know what to tell you, but here's how I always wrote my math. F'(x) = [(1/3)x]^-2/3 = 1/3rt(x) ^2 Sabra Ewing > On Apr 23, 2018, at 1:29 PM, dslab via BlindMath <blindmath at nfbnet.org> wrote: > > "F prime of ex equals one third ex to the negative two thirds equals one over three times the third root of ex squared."