Algebra 2 Advanced

Graphing Rational Functions

Complete analysis of a rational function — find all asymptotes, holes, intercepts, and domain, then graph it.

Live Calculator · Step-by-Step · Algebra 2
Enter Rational Function
Polynomials up to degree 2, integer coefficients. Use x² or x^2.
Examples
Analysis Results
Enter a numerator and denominator, then press Graph & Analyze to see all features of the rational function.
Domain
X-intercepts
Y-intercept
Vertical Asymptotes
Holes
Horizontal Asymptote
Oblique Asymptote
Step-by-Step Solution
Graph
f(x) curve
Vertical asymptote
Horiz/oblique asymptote
Hole
X-intercept
Y-intercept
Checklist for Graphing Rational Functions
  • Factor the numerator and denominator completely
  • Cancel common factors to simplify (creates holes)
  • Find x-intercepts: set simplified numerator = 0
  • Find y-intercept: evaluate f(0)
  • Find vertical asymptotes: simplified denominator = 0
  • Find horizontal or oblique asymptote (degree comparison)
  • Plot holes as open circles, then sketch branches
Asymptotes Are Guidelines, Not Walls
deg(num) = deg(den)+1 → oblique asymptote

Remember that asymptotes are guidelines, not walls — the function can sometimes cross a horizontal asymptote in the middle of the graph. The asymptote only describes the end behavior.

A vertical asymptote is different: the function never crosses it. The graph approaches but never reaches a vertical asymptote.

Degree rules for end behavior: If deg(num) < deg(den), HA is y = 0. If degrees are equal, HA is the ratio of leading coefficients. If deg(num) = deg(den) + 1, there is an oblique asymptote (use long division). If deg(num) > deg(den) + 1, there is no asymptote.

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