Maximum/Minimum

[abbycookies]

I am working on a stufy guide for my final exam and I forgot how to find maximums and minimums on an open interval. You take the derivative first right? then set it equal to zero? my problem is f(x)=x³-12x-5. i have the derivative and factored it to 3(x²-4) is this right? how would i do the next step?333335454354^33---hujhjih

 

[Deleted member 4993]

I am working on a stufy guide for my final exam and I forgot how to find maximums and minimums on an open interval. You take the derivative first right? then set it equal to zero? my problem is f(x)=x³-12x-5. i have the derivative and factored it to 3(x²-4) is this right? how would i do the next step?333335454354^33---hujhjih

3(x²-4) = 0

3(x-2)(x+2) = 0

Above equation is true for x = ±2

 

[abbycookies]

So the relative maximums and minimums are 2 and -2?

 

[Deleted member 4993]

So the relative maximums and minimums are 2 and -2?

No... relative maximum/minimum occur at x = ± 2

 

[Jason76]

This thread should answer the question:

http://www.freemathhelp.com/forum/threads/80717-Critical-Numbers-Inflection-Points-and-y-Values