How Do You Solve the Limit Using the Quotient Law?

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SUMMARY

The limit problem presented involves evaluating the expression lim (1/x - 1/3) / (x-3) as x approaches 3. The correct solution is -1/9, achieved by combining the fractions in the numerator and simplifying rather than attempting to cancel (x-3) directly. The confusion arises from the 0/0 indeterminate form, which can be resolved by finding a common denominator for the fractions in the numerator. This approach is essential for correctly applying the Quotient Law in calculus.

PREREQUISITES
  • Understanding of limits in calculus
  • Familiarity with the Quotient Law
  • Ability to manipulate algebraic fractions
  • Knowledge of indeterminate forms and L'Hôpital's Rule
NEXT STEPS
  • Study the process of finding limits using L'Hôpital's Rule
  • Learn how to combine fractions with different denominators
  • Practice solving limits that result in indeterminate forms
  • Explore the application of the Quotient Law in various calculus problems
USEFUL FOR

Students studying calculus, particularly those tackling limits and indeterminate forms, as well as educators looking for effective methods to teach these concepts.

Alice7979
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Homework Statement


lim (1/x - 1/3) / (x-3)
x->3

Homework Equations

The Attempt at a Solution


I tried to cancel the bottom (x-3) out by multiplying the top by 3/3 and x/x and then got ((3-x)/3x)/(x-3) but ended with 0/0 and the right answer is -1/9. The top part is confusing me.
 
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Alice7979 said:

Homework Statement


lim (1/x - 1/3) / (x-3)
x->3

Homework Equations

The Attempt at a Solution


I tried to cancel the bottom (x-3) out by multiplying the top by 3/3 and x/x and then got ((3-x)/3x)/(x-3) but ended with 0/0 and the right answer is -1/9. The top part is confusing me.
Combine the two fractions in the numerator, and then simplify. This problem isn't much more than an exercise in working with fractions.
 
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Like @Mark44 said, find a common denominator between ## \frac 1 x \text{ and } \frac 1 3 ##. Similar to if you were adding the fractions ## \frac 1 7 \text{ and } \frac 1 3 ##
 

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