Florida B.E.S.T. MA.912.C.1.5
The Standard
Find limits at infinity.
Florida B.E.S.T. Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students determine what function values approach as inputs grow without bound in either direction. They use graphs, tables, or dominant terms to support the result.
What Mastery Looks Like
- Students find limits as x approaches positive or negative infinity from formulas, graphs, and tables. They use dominant terms correctly and state when a limit is finite, infinite, or nonexistent.
Common Misconceptions
- Students may treat infinity as a number and try direct substitution. They may compare all terms instead of dominant terms, or assume both ends behave the same way.
How to Assess It
- Give this exit ticket: Find both end limits of f(x) = (3x² - 2)/(x² + 5), then justify using dominant terms.
Lesson moves
Ways to Teach It
Use a graphing calculator to make tables for large positive and negative inputs, then compare each function's end behavior.
Ask students to explain why lower-degree terms matter less as the input grows, using one rational function as evidence.
Play a card sort matching function formulas, graphs, dominant-term comparisons, and limits at positive and negative infinity.
Model long-term medication concentration with C(t) = 20t/(t + 4), then interpret the limit in context.
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Printable MA.912.C.1.5 Worksheet

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Related Standards
- MA.912.C.1.6
Decide when a limit is infinite and use limits involving infinity to describe asymptotic behavior.
- MA.912.C.1.4
Find one-sided limits.
- MA.912.C.1.3
Find limits of rational functions that are undefined at a point.
- MA.912.C.1.7
Find special limits by using the Squeeze Theorem or algebraic manipulation.
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