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Mathematics 13 Online
OpenStudy (anonymous):

Graphing an equation/function. f(x)= (-6)/(x+3) See attachment. @Calculus1

OpenStudy (anonymous):

OpenStudy (stacey):

Have you taken the derivative?

OpenStudy (anonymous):

Yes, (6)/(x+3)^2

OpenStudy (stacey):

Have you set equal to zero, to find any relative extrema?

OpenStudy (anonymous):

No, I got lost on that part. Would we use -3?

OpenStudy (stacey):

You're thinking. Actually, we can't get it to equal 0, but at x=-3, it is undefined. So x=-3 is a critical point.

OpenStudy (stacey):

More precisely x=-3 is a vertical asymptote.

OpenStudy (stacey):

And we have no local extrema.

OpenStudy (anonymous):

Horizontal asymptotes would be 0, right?

OpenStudy (anonymous):

at*

OpenStudy (stacey):

If you put a value in for x<3 into the first derivative, do you get a positive or a negative answer?

OpenStudy (anonymous):

Positive

OpenStudy (stacey):

Yes, the horizontal is at y=0.

OpenStudy (stacey):

What does the positive value for the derivative tell you about the function?

OpenStudy (anonymous):

It's increasing.

OpenStudy (stacey):

Correct. You should also check to see what the function is doing for x>-3.

OpenStudy (anonymous):

It's increasing. o.o

OpenStudy (stacey):

Great. Have you looked at concavity yet?

OpenStudy (anonymous):

Umm, no, got lost on that one two.

OpenStudy (anonymous):

Wait is it possible to be increasing on bot sides?

OpenStudy (anonymous):

both*

OpenStudy (stacey):

Yes.

OpenStudy (stacey):

If you have a fractional equation, such as (x+2)/(2x^2 + 3) = 0 and it is set equal to zero, you can ignore the denominator and solve the new equation x+2=0.

OpenStudy (anonymous):

Umm, the second derivative is (-12)/(x+3)^3 how do you find the inflection point?

OpenStudy (anonymous):

Does it have any?

OpenStudy (stacey):

Since the second derivative is -12/(x+3)^3 and we cannot have -12=0, so there are no inflection points.

OpenStudy (anonymous):

So I got this, it's increasing on [-inf,-3] and on [-3,inf] and it's not decreasing.

OpenStudy (stacey):

Those should be parenthesis instead of brackets.

OpenStudy (anonymous):

aaah okay, thanks! I think that's it. Thank you so much.

OpenStudy (stacey):

(-inf,-3) and on (-3,inf)

OpenStudy (stacey):

You're welcome.

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