Wednesday, 2 March 2016

limits - Which function grows faster?




Which function grows faster



𝑓(𝑛)=2𝑛2+3𝑛 and 𝑔(𝑛)=2𝑛+1



by using the limit theorem I will first simplify



then I will just get limn2n2+3n2n+1=limn2n2+3nn1=limn2n2+2n1=



Is this enough?
I say it will go then to infinity so the f(n) is growing faster? I am asking this question because I have to find it by using limit but I didn't need to use l'hopital rule!



Answer



Before Edit:
Your idea was correct, but you didn’t simplify the limit properly.
limn2n2+3n2n+1


It is enough to divide both the numerator and denominator by 2n.
limn2n2+3n2n2n+12n=limn2n2+3nn2nn+12n=limn2n2+2n1+12n

As n, it becomes clear that the limit tends to since the numerator tends to while the denominator tends to 1.



After Edit: Yes, your way is correct.


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