Thread: relative minimum

At what values of x does f(x) = x^4 - 8x^2 have a relative minimum.

A. 0 and -2 only
B. 0 and 2 only
C. 0 only
D. -2 and 2 only
E. -2, 0, and 2

Originally Posted by DINOCALC09

At what values of x does f(x) = x^4 - 8x^2 have a relative minimum.

A. 0 and -2 only
B. 0 and 2 only
C. 0 only
D. -2 and 2 only
E. -2, 0, and 2

step 1: find the first and second derivative

step 2: set the first derivative to zero and solve for x.

step 3: plug in your x-values from step 2 into the second derivative. the ones that give you a positive result are the points you want

so the answer should b D then?