Finding the Limit of tln(t) as t Approaches 0

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In summary, the derivative of sin(3x) is not just 3sin(3x) because the derivative of sine is not itself. The correct derivative would be 3cos(3x) due to the chain rule. For the limit of tln(t), one approach is to look for a minimum of the function and determine if it has one or more minima.
  • #1
mattmns
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Is the derivative of sin(3x) just 3sin(3x) because of the chain rule? IE, let u=3x, then 3sin(u) => 3sin(3x)

Thanks.
:cool:

Ok, I am pretty sure that is true. How about, [tex]

\lim_{t\rightarrow 0} tln(t)

[/tex]

What is the common approach for this problem?
 
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  • #2
mattmns said:
Is the derivative of sin(3x) just 3sin(3x) because of the chain rule? IE, let u=3x, then 3sin(u) => 3sin(3x)

Thanks.
:cool:

Ok, I am pretty sure that is true. How about, [tex]

\lim_{t\rightarrow 0} tln(t)

[/tex]

What is the common approach for this problem?
It's not true because the derivative of sine is not itself

For the limit, you might look for a minimum of the function. Does it have one? More than one? That should get you started.
 
  • #3
i agree with OlderDan.
[tex]h(x)=f(g(x))[/tex]
if you have that, then:
[tex]h'(x)=f'(g(x))*g'(x)[/tex]
so, sine is not the derivative of itself.
 
  • #4
I think the derivative of sine is cosine,
so the derivative of sin(3x) would be 3cos(3x)
 
  • #5
Bah, that is what I meant, sorry. Thanks, been a while since I did a derivative or a limit :cry:
 

What is the derivative of sin(3x)?

The derivative of sin(3x) is 3cos(3x).

How do you find the derivative of sin(3x)?

To find the derivative of sin(3x), you can use the chain rule. First, take the derivative of the outer function sin(x), which is cos(x). Then, multiply by the derivative of the inner function (3x), which is 3. This results in 3cos(3x).

Why is the derivative of sin(3x) equal to 3cos(3x)?

The derivative of sin(x) is cos(x), so when we apply the chain rule to sin(3x), we get 3cos(3x) as the derivative. This is because the 3 in front of the x is considered a constant, and the derivative of a constant is 0, leaving us with just cos(3x).

What is the graph of the derivative of sin(3x)?

The graph of the derivative of sin(3x) is a cosine curve with a period of 2π/3 and an amplitude of 3. It intersects the x-axis at every multiple of 2π/3 and the y-axis at (0,3).

What are the applications of the derivative of sin(3x)?

The derivative of sin(3x) has many applications in physics, engineering, and other scientific fields. It can be used to model the motion of a spring, the behavior of sound waves, and the analysis of electrical circuits, among other things.

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