Limit of Function at (-1,3): Does it Exist?

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The discussion centers on whether the limit of a function at the point (-1, 3) exists when the point itself is not included. It is clarified that the limit as x approaches -1 from the right is 3, while the limit from the left is 1. The existence of the overall limit at x = -1 is confirmed, despite the absence of the point itself. The conversation emphasizes that limits depend on the behavior of the function near the point, not the function's value at that point. Thus, the limit can exist even if the function is undefined at that specific location.
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Homework Statement


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Homework Equations


The Attempt at a Solution


If the dot (-1,3) is gone, does the limit of x->-1 exist??
 
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How do you conclude lim x->(-1)+ is 3? And why do you think lim x->(-1) doesn't exist?
 


Yeah, you should check E and F
you got f wrong because e is wrong
for e, why did you say that the answer is 3
if the question was f(-1) = ?, then the answer would be 3
 


no.., just ignore the answer
I know x->(-1)+ is 1
but is x->(-1) exist ,if the dot is gone?
 


Yes. The limit as x goes to a from below or above, or the limit as x goes to a, all depend only on the values of f(x) for x close to a, not at a. The value of f(a) is irrelevant to [/math]\lim_{x\to a} f(x)[/math] which may exist even if f(a) does not exist.
 
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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