help finding info about a function without knowing the actual function??? i

gallentlyspeaking

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help finding info about a function without knowing the actual function? (AP Calc AB)

given that f is continuous on [-2,5] and...
f(-2)=10

f(5)=6

f'(x) is positive on (-2. 1) and (3,5); negative on (1,3); 0 at x=1 and undefined at x=3

f''(x) is positive on (3, 5), negative on (-2, 1) and (1,3); 0 at x=0. and undefined at x=3

a)find intervals where f is increasing or decreasing
b) find where f has absolute extrema
c) find where f has points of inflection
d) find intervals where f is concave up and concave down



i tried working through it & got..


a) I: [2,-1] and (3,5] D: [1,3) (not sure about use of brackets vs parenthesis with the 3 since it's undefined??)

b) x=1 max, x=3 min based on my rough sketch of the graph..

c) IP at x=3? can this occur at an undefined???

d)cc up on (3, 5) cc down on (-2, 3).. but should the interval be more precise? is (3, 5) concave up??

please correct/guide me.. I really want to understand this for the AP exam!!!:D
 
Last edited:
given that f is continuous on [-2,5] and...
f(-2)=10

f(5)=6

f'(x) is positive on (-2. 1) and (3,5); negative on (1,3); 0 at x=1 and undefined at x=3

f''(x) is positive on (3, 5), negative on (-2, 1) and (1,3); 0 at x=0. and undefined at x=3

a)find intervals where f is increasing or decreasing
b) find where f has absolute extrema
c) find where f has points of inflection
d) find intervals where f is concave up and concave down

i tried working through it & got..

a) I: [2,-1] and (3,5] D: [1,3) (not sure about use of brackets vs parenthesis with the 3 since it's undefined??)
Isn't the function increasing only where the derivative is positive, not just non-negative? So should points outside the intervals of positivity be included, or excluded? Same question for the interval of negativity.

b) x=1 max, x=3 min based on my rough sketch of the graph..
I agree.

c) IP at x=3? can this occur at an undefined???
How does your book define "inflection point"?

d)cc up on (3, 5) cc down on (-2, 3).. but should the interval be more precise? is (3, 5) concave up??
The point where the second derivative is zero: is that included in the intervals of concavity? According to the definition here, no. What is your book's definition? Otherwise, I agree with your intervals. ;)
 
given that f is continuous on [-2,5] and...
f(-2)=10

f(5)=6

f'(x) is positive on (-2. 1) and (3,5); negative on (1,3); 0 at x=1 and undefined at x=3

f''(x) is positive on (3, 5), negative on (-2, 1) and (1,3); 0 at x=0. and undefined at x=3

a)find intervals where f is increasing or decreasing
b) find where f has absolute extrema
c) find where f has points of inflection
d) find intervals where f is concave up and concave down



i tried working through it & got..


a) I: [2,-1] and (3,5] D: [1,3) (not sure about use of brackets vs parenthesis with the 3 since it's undefined??)

b) x=1 max, x=3 min based on my rough sketch of the graph..

c) IP at x=3? can this occur at an undefined???

d)cc up on (3, 5) cc down on (-2, 3).. but should the interval be more precise? is (3, 5) concave up??

please correct/guide me.. I really want to understand this for the AP exam!!!:D
Please show us your graph.
 
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