• Nov 18th 2012, 10:54 AM
dusech3
How do i know when to plug limit into my calculator or solve algebraicaly
(Crying) I NEED HELP FINDING LIMITS ALGEBRAICALLY
lim t^3+8/t+2 t-->-2
• Nov 18th 2012, 11:04 AM
Plato
Quote:

Originally Posted by dusech3
I NEED HELP FINDING LIMITS ALGEBRAIALLY

Post a problem. No mind readers here.
• Nov 18th 2012, 11:08 AM
dusech3
lim tan3x/tan5x
x--->0
• Nov 18th 2012, 11:23 AM
MarkFL
For the first limit, try writing the numerator as the sum of 2 cubes.

For the second, barring the use of L'Hôpital's rule, try writing:

$\frac{\tan(3x)}{\tan(5x)}=\frac{3}{5} \cdot \frac{ \tan(3x)}{3x} \cdot \frac{5x}{ \tan(5x)}$
• Nov 18th 2012, 11:58 AM
HallsofIvy
Re: How do i know when to plug limit into my calculator or solve algebraicaly
Quote:

Originally Posted by dusech3
(Crying) I NEED HELP FINDING LIMITS ALGEBRAICALLY
lim t^3+8/t+2 t-->-2

The first thing you should try, to find $\lim_{x\to a} f(x)$ is calculating f(a). That doesn't work for this problem because both numerator and denominator are 0. And that $t^3+ 8$ is 0 when t= -2 [b]tells/b] you that it has a factor of t+ 2. That is, $t^3+ 8= (t+ 2)(t^2+ at+ b)$ for some a and b. What are they?