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1.03 Evaluating Limits Algebraically. Graphically ( √ ) Algebraically (starting this lesson) Using the Sandwich Theorem (later). Evaluating Limits. Direct substitution (easy!) Expand, simplify substitution Factor, simplify by reducing substitution
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Graphically (√) Algebraically (starting this lesson) Using the Sandwich Theorem (later) Evaluating Limits
Direct substitution (easy!) Expand, simplify substitution Factor, simplify by reducing substitution Combine to a single fraction, reduce substitute Simplify using multiplication by conjugate Simplify using “known” limits Ways to algebraically evaluate
Example 1 • Try direct substitution
Example 2 • Try direct substitution • (remember, we use RADIANS in calculus)
Example 3 • Direct substitution clearly gives us division by 0 • LIMIT IS NOT 0 !!!!
Example 3 • Expand and simplify • Notice that the “lim” stays in the work until you substitute
Example 4 • Try direct substitution • Doesn’t work… division by 0!
Example 4 • Factor and reduce
Example 5 • Factor and reduce
Example 6 • Check – does direct substitution work? • Division by zero • No common factors?
Example 6 • Use the “conjugate trick” • (or be clever and factor denominator)
Always perform a mental check to see if direct substitution will work right off the top… very ugly looking limits can actually be really easy! Pay careful attention to how you expand and how you reduce fractions Watch out