I am told to write the value of a the derivative at a certain point next to each function. And to find the point/s(adsbygoogle = window.adsbygoogle || []).push({});

f(x) = x^{2}

f ' (x) = -6

so I figured I just do

f ' (x) = 2x

f ' (-6) = 2 x (-6) = -12

But they tell me the answer is

(-3, 9)

**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!

# Homework Help: Weird result to a simple derivative question

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