**Re: MATH1131 help thread**

When x is large, f(x) "looks like" x/(2x^3) = 1/(2x^2), because the -1 on the denominator becomes negligible. So we know we want to compare f(x) to 1/(2x^2) (or can just do it to 1/x^2, since all we need is the limit of f(x)/g(x) to be a positive constant), and this is helpful because we know the convergence status of the improper integral of 1/(x^2).How do you know what function to pick out for g(x)?

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