I thought I should start numbering these... anyway, here's another brain-fart where I miss something obvious:(adsbygoogle = window.adsbygoogle || []).push({});

in the book the dude uses:

[tex]\[

f(x) = \frac{1}{{30}}\sqrt {a^2 + x^2 } + \frac{1}{{60}}(b - x)

\]

[/tex]

later on he continues, using:

[tex]\[

f'(x) = \frac{1}{{30}}\frac{1}{2}(a^2 + x^2 )^{ - 1/2} (2x) - \frac{1}{{60}}

\]

[/tex]

where'd that 2x come from? isn't the derivative of [tex]\[

\sqrt {a^2 + x^2 }

\][/tex] just [tex]\[

\frac{1}{2}(a^2 + x^2 )^{ - 1/2}

\][/tex]?

thanks

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

Dismiss Notice

Join Physics Forums Today!

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

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

# Attack of my horrid math skills, pt. 1

Loading...

Similar Threads for Attack horrid math |
---|

I surface area of a revolution, why is this wrong? |

What is tensor calculus? |

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