Math Problem Statement

Evaluate the limit: lim (x→5) (50 - 2x^2) / (x - 5)

Solution

The limit you're trying to evaluate is:

limx5502x2x5\lim_{x \to 5} \frac{50 - 2x^2}{x - 5}

To solve this, follow these steps:

Step 1: Direct Substitution

Substitute x=5x = 5 directly into the expression:

502(5)255=50500=00\frac{50 - 2(5)^2}{5 - 5} = \frac{50 - 50}{0} = \frac{0}{0}

Since this results in an indeterminate form 00\frac{0}{0}, we need to apply further techniques like factoring, simplifying, or using L'Hôpital's Rule.

Step 2: Factorization or Simplification

Let's first simplify the numerator 502x250 - 2x^2. We observe that:

502x2=2(25x2)50 - 2x^2 = 2(25 - x^2)

We can factor 25x225 - x^2 as a difference of squares:

25x2=(5x)(5+x)25 - x^2 = (5 - x)(5 + x)

So, the expression becomes:

2(5x)(5+x)x5\frac{2(5 - x)(5 + x)}{x - 5}

Notice that 5x5 - x can be rewritten as (x5)-(x - 5), so:

2((x5))(5+x)x5=2(x5)(5+x)x5\frac{2(-(x - 5))(5 + x)}{x - 5} = \frac{-2(x - 5)(5 + x)}{x - 5}

The x5x - 5 terms cancel out (since x5x \neq 5):

limx52(5+x)\lim_{x \to 5} -2(5 + x)

Step 3: Evaluate the Limit

Substitute x=5x = 5 into the simplified expression:

2(5+5)=2(10)=20-2(5 + 5) = -2(10) = -20

Final Answer:

limx5502x2x5=20\lim_{x \to 5} \frac{50 - 2x^2}{x - 5} = -20

Would you like further details or have any questions about this solution?

Here are some related questions to expand your understanding:

  1. What are the conditions under which L'Hôpital's Rule can be applied to solve limits?
  2. How do you factor the difference of squares in general?
  3. What is the importance of checking for indeterminate forms when evaluating limits?
  4. Can limits always be solved by direct substitution?
  5. How does the behavior of a function near a point affect the limit at that point?

Tip: When you encounter an indeterminate form like 00\frac{0}{0} in limits, consider factoring, simplifying, or applying L'Hôpital's Rule to resolve it.

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Math Problem Analysis

Mathematical Concepts

Limits
Factorization
Indeterminate Forms
Difference of Squares

Formulas

Factorization of Difference of Squares: a^2 - b^2 = (a - b)(a + b)
L'Hôpital's Rule

Theorems

L'Hôpital's Rule

Suitable Grade Level

Grades 11-12