2006-10-09 10:03:40 · 3 answers · asked by kiki 1 in Science & Mathematics ➔ Mathematics
There seems to be a typo in this question. Do you mean f(x)=2x^2-k/x? Please clarify.
Regardless, the approach to take is to compute the second derivative, plug in x=-1, and set it equal to zero. Then solve for k.
2006-10-09 10:07:00 · answer #1 · answered by James L 5 · 0⤊ 0⤋
James L is correct except he means the 1'st derivative. The 2'nd derivative is used to tell if it's a minimum, maximum, or inflection point. But the problem already told you it was an inflection point so you really need the 1'st derivative set to 0 at x = -1.
Doug
2006-10-09 17:13:58 · answer #2 · answered by doug_donaghue 7 · 0⤊ 1⤋
The first answer is right. You have to calculate the second derivative and verify that there is a sign change in x = -1.
When the first derivative is 0, this shows a maximum or a minimum iff the second derivative is different from 0 or iif there is a sign change in the first one. If both derivatives are 0, then you have an inflexion point whose tangent is horizontal.
Ana
2006-10-10 22:31:32 · answer #3 · answered by Ilusion 4 · 0⤊ 0⤋