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# Increasing and decreasing functions watch

1. Find the values of x for which f(x) is an increasing function, given that f(x) equals:
A) x^4+2x^2
B) x^4-8x^3

I understand that you have to differentiate and then solve the equation but I can't get a proper answer
2. yes you differentiate then solve

dy/dx > 0 for increasing

dy/dx < 0 for decreasing
3. As the bear says, solve the inequalities to get answers. Be very careful when you give your final answers, make sure they are the correct inequalities. It may help to sketch the graphs as well.
4. (Original post by the bear)
yes you differentiate then solve

dy/dx > 0 for increasing

dy/dx < 0 for decreasing
Techinially the inequalities should not be strict because the question doesn't ask for where the functions are strictly increasing/decreasing.

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Updated: January 29, 2017
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