Math Problem Statement

lim_{x→1} |2 - x| / (x^2 - 3x + 2).

Solution

The given limit is:

limx12xx23x+2.\lim_{{x \to 1}} \frac{|2 - x|}{x^2 - 3x + 2}.

Let's solve this step by step.

Step 1: Factorize the denominator

The denominator x23x+2x^2 - 3x + 2 can be factored as follows:

x23x+2=(x1)(x2).x^2 - 3x + 2 = (x - 1)(x - 2).

So, the expression becomes:

2x(x1)(x2).\frac{|2 - x|}{(x - 1)(x - 2)}.

Step 2: Handle the absolute value

The expression inside the absolute value is 2x2 - x. To simplify the limit, consider how the absolute value behaves depending on whether xx approaches 1 from the left (x1x \to 1^-) or from the right (x1+x \to 1^+).

  • If x1x \to 1^- (approaching from values less than 1), 2x>02 - x > 0, so 2x=2x|2 - x| = 2 - x.
  • If x1+x \to 1^+ (approaching from values greater than 1), 2x<02 - x < 0, so 2x=x2|2 - x| = x - 2.

Step 3: Evaluate the one-sided limits

(a) Left-hand limit (x1x \to 1^-):

For x1x \to 1^-, we use 2x=2x|2 - x| = 2 - x. The expression becomes:

limx12x(x1)(x2).\lim_{{x \to 1^-}} \frac{2 - x}{(x - 1)(x - 2)}.

Notice that when x1x \to 1^-, x1<0x - 1 < 0. Therefore, the denominator will approach zero from the negative side, while the numerator 2x2 - x approaches 1.

Hence, the left-hand limit will be:

limx11(11)(12)=.\lim_{{x \to 1^-}} \frac{1}{(1 - 1)(1 - 2)} = -\infty.

(b) Right-hand limit (x1+x \to 1^+):

For x1+x \to 1^+, we use 2x=x2|2 - x| = x - 2. The expression becomes:

limx1+x2(x1)(x2).\lim_{{x \to 1^+}} \frac{x - 2}{(x - 1)(x - 2)}.

In this case, the numerator x2x - 2 is negative as x1+x \to 1^+, and x1x - 1 is positive. So the overall expression approaches:

limx1+1(11)(12)=.\lim_{{x \to 1^+}} \frac{-1}{(1 - 1)(1 - 2)} = \infty.

Step 4: Conclusion

Since the left-hand limit approaches -\infty and the right-hand limit approaches \infty, the overall limit does not exist.


Would you like more details on a particular part of the solution, or do you have any further questions?

Here are five related questions to deepen your understanding:

  1. How do you deal with absolute values in limits when the limit point is near a critical point?
  2. What is the significance of one-sided limits in determining the overall limit?
  3. Why does factoring polynomials help in limit problems like this one?
  4. How can you apply L'Hôpital's Rule to problems involving limits with indeterminate forms?
  5. Can limits approach infinity in real-world scenarios, and how are such cases interpreted?

Tip: When dealing with limits involving absolute values, always consider the behavior of the function from both sides (left-hand and right-hand limits) separately.

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Math Problem Analysis

Mathematical Concepts

Limits
Absolute Value
Factoring

Formulas

Factoring quadratic: x^2 - 3x + 2 = (x - 1)(x - 2)
Handling absolute value
One-sided limits

Theorems

Limit laws
One-sided limit evaluation

Suitable Grade Level

Grades 11-12 (Pre-Calculus/Calculus)