wow! I am having a major brain fart here .. I'm in multivariable calc but I need to take the derivative of a single variable function using the definition of derivative. The function is:(adsbygoogle = window.adsbygoogle || []).push({});

f(x)=abs(x)^(3/2) and I need to find the derivative when a=0

so by the def of derivative, the derivative equals:

lim (h->0) of [abs(a+h)^(3/2)-abs(a)^3/2]/h

I know I'm not allowed to just "plug in" a=0 to get the derivative at this point .. but how do I do it? I can't combine the absolute value terms because of the triangle inequality (for ex. abs(-6)-abs(3)=3 but abs(-6-3)=9)

help! I feel really stupid right now. :grumpy:

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Simple Single Variable Derivative Question

**Physics Forums | Science Articles, Homework Help, Discussion**