find the inflection points when f'=(x+4)(5-x)(x-10)

Question

zepdrix · Answer

Hmmmm to find inflection points I guess we need to take the second derivative huh? :D

I suppose doing a product rule type thing might be easier than factoring this out? :D

anonymous · Answer

Well, I tried factoring it, and using the quadratic equation... and that's not the answer.  I can't figure it out!!

zepdrix · Answer

ok lets try taking the derivative, but with 3 functions!
its very similar to the product rule that you're familiar with.
two variables (uv)'=u'v + uv'
3 variables (uvw)' =u'vw + uv'w + uvw'

You are familiar with the product rule yes? :o

anonymous · Answer

Yes, so how would that work?  Would the 2nd derivative be -1?

anonymous · Answer

no point of inflexion ... in this case here

anonymous · Answer

Wll there are minimum and maximum points, so it must change concavity.  Also, my homework wants 2 inflection points!  I just can't freaking figure them out!!