MHB Show $\displaystyle \lim_{x \to \infty} \frac{50x^{10}+100}{x^{11}+x^6+1}=0$

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How do you show that $\displaystyle \lim_{x \to \infty} \frac{50x^{10}+100}{x^{11}+x^6+1}=0$

What I tried:

$\displaystyle \lim_{x \to \infty} \frac{50x^{10}+100}{x^{11}+x^6+1} =\lim_{x \to \infty} \frac{50+100/x^{11}}{1+1/x^{5}+1/x^{11}} = \frac{50+0}{1+0+0} = 50.$

But this is wrong. (Angry)
 
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If you have a fraction of polynomials and you want to find the limit as $x \to +\infty$ you look only at the terms of largest degree.

So your limit is equal to $\lim_{x \to +\infty} \frac{50 x^{10}}{x^{11}}=\lim_{x \to +\infty} \frac{50}{x}=0$
 
evinda said:
If you have a fraction of polynomials and you want to find the limit as $x \to +\infty$ you look only at the terms of largest degree.

So your limit is equal to $\lim_{x \to +\infty} \frac{50 x^{10}}{x^{11}}=\lim_{x \to +\infty} \frac{50}{x}=0$
Thanks. When is it that we divide the highest power then?
 
Guest said:
Thanks. When is it that we divide the highest power then?

You could also divide by the highest power in this case, if you would want to. The result will be the same...
 
evinda said:
You could also divide by the highest power in this case, if you would want to. The result will be the same...
I get it now - my algebra was wrong in the original post.

$\displaystyle \lim_{x \to \infty} \frac{50x^{10}+100}{x^{11}+x^6+1} =\lim_{x \to \infty} \frac{50/x+100/x^{11}}{1+1/x^{5}+1/x^{11}} = \frac{0+0}{1+0+0} = 0$

Thanks, again.
 

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