Find the intervals in which `f(x)=x^3-12 x^2+36 x+17` is increasing or decreasing.

Explanation

For `f(x)` to be increasing, we must have

`f
′
(x)>0`

`⟹3(x−6)(x−2)>0`

`⟹x<2` or `x>6`

`⟹x in (−oo,2)cup(6,oo)`

So, `f(x)` is increasing on `(−oo,2)cup(6,oo)`
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