Math Problem Statement

[5 points] Evaluate the following limit in terms of the constant a. limx→a. (x2 − a2)/(x^2 − 3ax + 2a^2)

Solution

We are tasked with evaluating the limit:

limxax2a2x23ax+2a2\lim_{x \to a} \frac{x^2 - a^2}{x^2 - 3ax + 2a^2}

Step 1: Factorize the expression

Numerator:

The numerator x2a2x^2 - a^2 is a difference of squares, which can be factorized as:

x2a2=(xa)(x+a)x^2 - a^2 = (x - a)(x + a)

Denominator:

The denominator x23ax+2a2x^2 - 3ax + 2a^2 can be factorized by recognizing it as a quadratic expression. We need to find factors of x23ax+2a2x^2 - 3ax + 2a^2.

Factoring gives:

x23ax+2a2=(xa)(x2a)x^2 - 3ax + 2a^2 = (x - a)(x - 2a)

Step 2: Simplify the expression

Now we can rewrite the original limit as:

limxa(xa)(x+a)(xa)(x2a)\lim_{x \to a} \frac{(x - a)(x + a)}{(x - a)(x - 2a)}

For xax \neq a, we can cancel out the common factor (xa)(x - a):

limxax+ax2a\lim_{x \to a} \frac{x + a}{x - 2a}

Step 3: Substitute x=ax = a

Now, substitute x=ax = a into the simplified expression:

a+aa2a=2aa=2\frac{a + a}{a - 2a} = \frac{2a}{-a} = -2

Thus, the value of the limit is:

2\boxed{-2}

Let me know if you want further details or explanations.

Here are 5 related questions:

  1. What happens if the limit involves a different factorization pattern in the denominator?
  2. How would the result change if a=0a = 0?
  3. Can L'Hopital's rule be applied in this situation? Why or why not?
  4. How can limits be used to determine continuity of a function?
  5. How do limits of rational functions behave near vertical asymptotes?

Tip: When solving limits involving rational expressions, always look for opportunities to factorize and simplify before direct substitution.

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Math Problem Analysis

Mathematical Concepts

Limits
Factoring
Algebraic Expressions
Rational Functions

Formulas

Difference of squares: x^2 - a^2 = (x - a)(x + a)
Factoring quadratic expressions: x^2 - 3ax + 2a^2 = (x - a)(x - 2a)

Theorems

Limit definition and properties
Factoring techniques

Suitable Grade Level

Grades 10-12