- #1
Dramacon
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Homework Statement
I'd always used the 2nd derivative test for the nature of stationary points. But I came across this equation in one of my exercises, for which the test doesn't seem to work at all.
Find the stationary points of: y=(x^2-1)4, stating the nature of each.
Homework Equations
Using normal calc: the stationary points are at (-1,0), (0,1) and (1,0)
The Attempt at a Solution
Although the double derivative works for when x=0, (local max)
When I sub in the values x=1 or x=-1, the value I end up with is 0: suggesting that these points are stationary points of inflection, when they are not (they're actually local minima).
Please help. :)