## AravindG 3 years ago find maximum and minimum values for the function g(x)=x^3-3x

1. AravindG

@hartnn

2. hartnn

what u got as first derivative ?

3. AravindG

3x^2-3=0 x^2=1 x=1,-1

4. AravindG

should i take second derivative?

5. hartnn

correct. here u can just put the values in g(x) and by inspection u can tell which is max

6. hartnn

mathematically, u should take 2nd derivative...

7. AravindG

max at x=-1 and minimum at x=1

8. AravindG

bt then why we took second derivative in last qn?

9. hartnn

because we can't find the max or min just by putting the points and inspection, can we ?

10. AravindG

i see is my final answers ryt?

11. AravindG

....

12. AravindG

u dr??

13. hartnn

sorry, got disconnected...yes, its correct

14. AravindG

one last qn and i am done ,,well for this qn i think i gt crct anser bt i want t o knw if i need to take second derivative "find maximum and minimum value of 3x^4-8x^3+12x^2-48x+25

15. AravindG

,,,

16. hartnn

yes, u need to..

17. AravindG

18. hartnn

mim at x=2

19. AravindG

max at x=0 min at x=2 ryt?

20. hartnn

yes, both are correct..i had doubt with max at x=0

21. AravindG

thanx a lot!!!! it really helped cant tell u hw thankful i am !!

22. AravindG

seeya gn8 sweeet drms