SOLUTION: Consider the function f(x) = x-3ln(x), 1/3 <= x <= 9 The absolute maximum value is ___ at x = ___ The absolute minimum value is ___ at x = ___ I know I need to find the CP

Algebra.Com
Question 1204526: Consider the function f(x) = x-3ln(x), 1/3 <= x <= 9
The absolute maximum value is ___ at x = ___
The absolute minimum value is ___ at x = ___
I know I need to find the CP
f'(x) = 1 - 3/x
1-3/x = 0
1 = 1/3x
x = 3
and there are the end points at 0 and 9
f(0) = 1/3 - 3ln(1/3) = 1/3 + 3ln(3)
f(3) = 3 - 3ln(3)
f(9) = 9 - 3ln(9) = 9 - 6ln(3)
However, I put these answers in and the autograder says they are incorrect and any help is appreciated :)



Found 3 solutions by ikleyn, MathLover1, greenestamps:
Answer by ikleyn(52832)   (Show Source): You can put this solution on YOUR website!
.

In your solution  (in your post),  you say that the end points are at  0  and  9.

It is    .   The endpoints are  1/3  and  9.


Your work should be re-done.



Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!

your interval is NOT

GLOBAL (ABSOLUTE) MINIMA
(,)=(,)
GLOBAL (ABSOLUTE) MAXIMA
(,)=(,)
download

Answer by greenestamps(13203)   (Show Source): You can put this solution on YOUR website!


In the work you show, you show endpoints of 0 and 9, when in fact they are 1/3 and 9. Where you say your are evaluating f(0), you are in fact correctly evaluating f(1/3).

And you don't show us what answers you actually put in that the autograder said were not correct.

There is only one absolute minimum and only one absolute maximum; we can't tell from your post what you said they were.

The minimum is at x=3; and f(1/3) is greater than f(9), so the maximum is at x=1/3.


RELATED QUESTIONS

Consider the function f(x) = x-3ln(x), 1/3 <= x <= 9 The absolute maximum value is ___ (answered by ikleyn)
Consider the function f(x)= 2-4^2 , -4 (answered by stanbon)
Consider the function f(x)=2x^3+18x^2−42x+11,−7≤x≤2 Find the... (answered by ikleyn)
Consider the function f(x) = 2x² - 20x – 1. What is the minimum value and it... (answered by scott8148)
Find the absolute maximum and minimum of the function {{{ f(x)= x^(1/3)*(x^2-9)}}} for... (answered by richard1234)
Find the intercepts of the absolute value function... (answered by solver91311)
Find the absolute maximum and the absolute minimum of f (x) = x2 − 6x + 9 on the... (answered by oscargut)
what is the range of absolute value x-1 divided by non absolute value... (answered by htmentor)
What is the vertex of the absolute value function f(X)=- the absolute value of X-5 -3,... (answered by MathLover1,greenestamps)