# Find convergence by using taylor series

• September 20th 2009, 01:48 PM
Zocken
Find convergence by using taylor series
$\lim_{x\to 0}\frac{cosx-cos(3x)}{sin(x^2)}$

I'm having trouble finding things to cancel out to get the right answer.

and also

$si(x)=\int_{0}^{x} \frac{sin(t)dt}{t}$

$\lim_{x\to 0} \frac{si(x)-x}{x^3}$

Same thing
• September 20th 2009, 02:07 PM
redsoxfan325
Do you have to use taylor series, or can you use other methods?
• September 20th 2009, 02:08 PM
Zocken
My professor said do by series