Solving limits with trig. functions

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Homework Help Overview

The discussion revolves around solving limit problems involving trigonometric functions and hyperbolic sine. Participants are attempting to evaluate limits as variables approach zero, specifically focusing on expressions that include sinh and trigonometric functions like sine and cotangent.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss splitting the limit problems into separate components to simplify evaluation. There is a suggestion to check for potential typos in the expressions, particularly regarding the use of cotangent. Questions arise about how to manipulate the limits to resemble known forms, such as lim x->0 sinx/x=1.

Discussion Status

The discussion is ongoing, with participants providing feedback on each other's reasoning and calculations. Some guidance has been offered regarding the splitting of limits and the validity of manipulating constants within limits. However, there is no explicit consensus on the correct approach or final evaluation of the limits.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the amount of direct assistance they can provide. There are indications of algebraic errors and misunderstandings that are being addressed throughout the discussion.

mybrainhurts1
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Can anyone help me with these two limit problems...
solve:

lim h->o (h^2-h+sinh)/2h

and

lim y->0 (sin3cot5y)/ycot4y

I know lim x->0 sinx/x=1, but I can't figure out how to get these two into that format.
 
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mybrainhurts1 said:
Can anyone help me with these two limit problems...
solve:

lim h->o (h^2-h+sinh)/2h
Split it up into the sum of three separate limits.
mybrainhurts1 said:
and

lim y->0 (sin3cot5y)/ycot4y
Typo here? Should this be lim y->0 (sin3ycot5y)/ycot4y?
If so, split it up into the product of three separate limits, after working with cot5y and cot4y.
mybrainhurts1 said:
I know lim x->0 sinx/x=1, but I can't figure out how to get these two into that format.
 
Yes, should be lim y->0 (sin3ycot5y)/ycot4y

So for the first problem--
(h^2/1)-(h/2)+sinh/h= (0^2/1)-(0/2)+1=1...?
 
No.
First, you omitted the fact that a limit is involved.
Second, you have multiple algebra errors.
 
You're very helpful.
 
Are you able to find the errors in the first problem?
 
limx->o h^2/2h - limx->0 h/2h + limx->0 sinh/2h, but where do I go from here.
 
[tex]\lim_{h \to 0} \frac{h^2}{2h} = (1/2) \lim_{h \to 0} h * \frac{h}{h}=(1/2) \lim_{h \to 0} h * \lim_{h \to 0}\frac{h}{h}[/tex]

It's valid to move constants in or out of the limit, and it's valid to split up limits into sums or products of limits, as long as the individual limits exist.

Can you continue from here for this limit and the other two?
 

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