#Not sure how the problem solving logic works here

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left moth
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safe anchor
# left moth

To check whether a piecewise function is continuous, you need to check for continuity on the boundary points of the pieces. So, here you need to ensure:
f(-1-) = f(-1+)
f(2-) = f(2+)

fading finch
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And combining (1) (2) and (3) you find the answer

left moth
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I previously understood this but I'm forgetting for some reason

safe anchor
left moth
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so what they're basically using is condition 2 (limit of f(x) exists) in order to solve for m and n, but what would theoretically happen if the limit did not exist?

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also I'm starting to hate this question the more I look at it because of it's ambiguity

safe anchor
left moth
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didn't indicate that the function was continuous, but instead asked to make it continuous

safe anchor
left moth
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wait a minute is that why they set both limits equal to eachother?

safe anchor
left moth
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in order to make it continuous?

safe anchor
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Yes.

left moth
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but then why'd they throw in a -5 in there

safe anchor
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In the statement?

left moth
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x>= -5

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what purpose does that serve

safe anchor
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Because the function is only defined for x ≥ -5.

left moth
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not sure i understand

safe anchor
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The domain of the function is x ≥ -5.

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So, it only makes sense to talk about continuity on that set, not a larger one, as the function isn't defined outside of it.

left moth
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hm okay, so it basically serves no purpose

safe anchor
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Well, continuity is looked at on a certain set.

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For example, if we have f(x) = 1/x, then it's continuous on its domain, but it clearly isn't continuous on the whole line.

left moth
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okay let me try breaking down the logic of this question then:

  • You need to make a non continuous function continuous
  • To do so, you must set the limits of the end points equal to one another
  • After you set the limits of the end points equal to one another you will find "m" and "n" by taking the limits for both sides
  • Subtracting "m" and "n" to isolate for one variable will serve as a substitution and an answer to make the function g(x) continuous
safe anchor
left moth
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only the first two steps are the thinky partsw

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now you wouldn't do this unless you wanted to make the function continuous because setting two limits equal to one another is basically saying "yes this function is continuous at this value"

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I think i get it now

safe anchor
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Great!

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Maybe a simpler exercise would be better as the starting one.

left moth
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hm okay wait

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can a continuous function contain a hole?

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because that's what I'm seeing in both of these points picked

safe anchor
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Find the values of m and n for which this function is continuous:
f(x) = ...
...m(x - 1)^2 - n + 10, x < 0
...1, x = 0
...2m(x + 1)^3 - n, x > 0

safe anchor
left moth
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so then how come they're letting x=2?

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isn't the fxn undefined at 2?

safe anchor
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Oh, hold on. Now that I see it, yeah.

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Yeah, they probably made a mistake there.

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Either the second or the third piece needs to also be defined on x = 2.

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Well, most likely they did mean that, otherwise the question is trivially answered with "no values of m and n work".

left moth
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haha well, this is the second mistake i've found on this test so far

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Thanks for your help though, understand it a lot better

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+close