Math Problem Statement

What is the limit of the expression lim_{x → 1/2} [(2x^3 - 1) / ((8x^2 + 2)(5x - 5)) - (2 - 5x) / (x^4 - 5x + 1)]?

Solution

The text extraction from the image was not successful again, so I'll analyze the limit expression directly from the image.

The limit is given as:

limx12[2x31(8x2+2)(5x5)25xx45x+1]\lim_{{x \to \frac{1}{2}}} \left[ \frac{2x^3 - 1}{(8x^2 + 2)(5x - 5)} - \frac{2 - 5x}{x^4 - 5x + 1} \right]

Approach:

  1. Substitute x=12x = \frac{1}{2} into both parts of the expression.

    • In the first term: = \frac{2\left(\frac{1}{8}\right) - 1}{(8\left(\frac{1}{4}\right) + 2)(5\left(\frac{1}{2}\right) - 5)} = \frac{\frac{1}{4} - 1}{(2 + 2)(\frac{5}{2} - 5)} = \frac{-\frac{3}{4}}{(4)(-\frac{5}{2})} = \frac{-\frac{3}{4}}{-10} = \frac{3}{40}$$
    • In the second term: = \frac{2 - \frac{5}{2}}{\frac{1}{16} - \frac{5}{2} + 1} = \frac{-\frac{1}{2}}{\frac{1}{16} - \frac{10}{4} + 1} = \frac{-\frac{1}{2}}{-\frac{27}{16}} = \frac{8}{27}$$
  2. Combine the two expressions: limx12(340827)\lim_{{x \to \frac{1}{2}}} \left( \frac{3}{40} - \frac{8}{27} \right)

    To subtract these two fractions, we first find a common denominator:

    • The least common denominator (LCD) of 40 and 27 is 1080.
    • Convert each fraction: 340=811080,827=3201080\frac{3}{40} = \frac{81}{1080}, \quad \frac{8}{27} = \frac{320}{1080}
  3. Subtract the fractions: 8110803201080=2391080\frac{81}{1080} - \frac{320}{1080} = \frac{-239}{1080}

Thus, the limit is:

2391080\boxed{\frac{-239}{1080}}

Would you like further clarifications on this process?

Here are five related questions to enhance your understanding:

  1. How do you approach finding limits involving complex fractions?
  2. What is the importance of substituting directly in a limit problem?
  3. How do you find a least common denominator when subtracting fractions?
  4. When is it appropriate to factor in order to simplify a limit problem?
  5. How do you handle indeterminate forms that involve subtraction?

Tip: Always simplify

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Math Problem Analysis

Mathematical Concepts

Limits
Substitution
Fraction Operations
Simplification

Formulas

Direct Substitution in Limits
Fraction Subtraction: a/b - c/d = (ad - bc) / bd

Theorems

Limit Theorem: lim_{x → c} [f(x) - g(x)] = lim_{x → c} f(x) - lim_{x → c} g(x) if both limits exist.

Suitable Grade Level

Grades 11-12