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Mathematics 18 Online
OpenStudy (anonymous):

Determine whether the sequence is increasing, decreasing, or not monotonic.

OpenStudy (anonymous):

Okay plz post the problem

OpenStudy (anonymous):

\[a_n = \frac{ 7n-8 }{ 8n +3 }\]

OpenStudy (anonymous):

don't be confused the "sequence" part of this imagine you were graphing \[f(x)=\frac{7x-8}{8x+3}\] would it be increasing, decreasing or neither on \(0,\infty\)?

OpenStudy (anonymous):

if it is not clear, you can take the derivative and check

OpenStudy (anonymous):

I know that the denom is increasing, and that could mean the seq is decreasing but the numerator throws me off

OpenStudy (anonymous):

what is the derivative ? what does the rational function look like?

OpenStudy (anonymous):

MAXIMUM AND MINIMUM VALUES is that what u are learning

OpenStudy (anonymous):

no

OpenStudy (anonymous):

no not at all it is asking if it is increasing or decreasing or neither

OpenStudy (anonymous):

did you find the derivative yet?

OpenStudy (anonymous):

I did not take that approach, no. I was trying to see if the numerator was also increasing. and if they both are increasing, does that mean that the seq is increasing

OpenStudy (anonymous):

no

OpenStudy (anonymous):

just because they are both increasing doesn't mean the terms are for example x and x^2 + 1 are both increasing, but \(\frac{x}{x^2+1}\) would be decreasing on \((0,\infty)\)

OpenStudy (anonymous):

are you reluctant to take the derivative? if so, why?

OpenStudy (anonymous):

ok...i can see that when put that way!

OpenStudy (anonymous):

it just did not cross my mind. this professor does not teach, he just posts hw and says good luck

OpenStudy (anonymous):

let me know what you get

OpenStudy (anonymous):

or 7/8

OpenStudy (anonymous):

hmm forgot the quotient rule already that is the limit, not the derivative

OpenStudy (anonymous):

Determine the first derivative. If it is positive, then the function is increasing. If it is negative, the function is decreasing. The quotient rule for differentiating is

OpenStudy (anonymous):

\[\frac{ 85 }{ 64x^2+48x+9 }\]

OpenStudy (anonymous):

If\[f(x) = \frac{ g(x) }{ h(x) } \text{ then}\]\[f^\prime (x) = \frac{ g^\prime (x) h(x) - g(x) h^\prime (x) }{ (h(x))^2 }\]

OpenStudy (anonymous):

ok. thank you

OpenStudy (anonymous):

so, the answer is increasing and bounded

OpenStudy (anonymous):

yes it is

OpenStudy (anonymous):

the denominator is a square, and the numerator is positive do the derivative is positive that makes the terms monotone increasing, and the limit is \(\frac{7}{8}\)

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