d/db (0.8 -b - 0.6 m)^2 (0.45-b - 0.35 m)^2 (0.1-b - 0.1 m)^2

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.