Short answer
What should you know first?
Graph behavior on the GRE Mathematics Subject Test gets much faster when you recognize families, asymptotes, intercept behavior, and end behavior before grinding algebra. This page focuses on seeing structure in the graph instead of treating every curve like a fresh puzzle.
Why it matters
Why this topic changes the rest of your prep.
ETS notes that some difficult math questions still rely mostly on strong precalculus. Graph behavior is one of the main reasons that is true.
Must know
Facts and heuristics that should start feeling automatic.
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Check the original form before declaring an asymptote removable.
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Multiplicity affects whether a graph crosses or only touches an axis.
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Exponential growth eventually outruns polynomial growth.
Useful cue
Use recognition before algebra when the graph family is obvious.
Worked example
One representative example.
For $$f(x)=\frac{x-1}{x+2}$$, identify the x-intercept, vertical asymptote, and horizontal asymptote.
Long route
The numerator gives x-intercept $$x=1$$. The denominator gives vertical asymptote $$x=-2$$. Equal degrees mean the horizontal asymptote is the ratio of leading coefficients, so $$y=1$$.
Fast route
Top zero gives intercept, bottom zero gives vertical asymptote, equal degrees give $$y=1$$.