Math Problem Statement

Evaluate the integral integral, from, minus, 9, to, 7, of, start fraction, minus, 2, divided by, left parenthesis, x, minus, 3, right parenthesis, start superscript, one third, end superscript, end fraction, d, x∫ −9 7 ​

(x−3) 3 1 ​

−2 ​ dx or state that the integral diverges.

Solution

The given integral is:

972(x3)13dx\int_{-9}^{7} \frac{-2}{(x - 3)^{\frac{1}{3}}} \, dx

This integral involves a fractional power of (x3)(x - 3), which could indicate a potential issue if the denominator becomes zero or undefined at any point. Let's first examine the behavior of the integrand, particularly around x=3x = 3.

Step 1: Identify potential issues

The function 2(x3)13\frac{-2}{(x - 3)^{\frac{1}{3}}} is undefined at x=3x = 3, because when x=3x = 3, the denominator becomes zero, and the fractional exponent 13\frac{1}{3} leads to a cube root of zero, which is a singularity.

Since the integral has limits from 9-9 to 77, and the function is undefined at x=3x = 3, the integral will involve a singularity at this point. This suggests that the integral might diverge.

Step 2: Test the nature of the singularity

To confirm if the integral diverges, we split the integral at the singularity, x=3x = 3:

972(x3)13dx=932(x3)13dx+3+72(x3)13dx\int_{-9}^{7} \frac{-2}{(x - 3)^{\frac{1}{3}}} \, dx = \int_{-9}^{3^-} \frac{-2}{(x - 3)^{\frac{1}{3}}} \, dx + \int_{3^+}^{7} \frac{-2}{(x - 3)^{\frac{1}{3}}} \, dx

We now need to examine the limits as xx approaches 3 from both sides.

Step 3: Check the behavior near x=3x = 3

To evaluate if the integral converges or diverges near x=3x = 3, consider the integrand near this point.

As x3x \to 3, the expression (x3)13(x - 3)^{\frac{1}{3}} behaves like a cube root, which means that the integrand will become unbounded (infinite) near x=3x = 3.

Step 4: Conclusion

Since the integrand behaves like 1(x3)13\frac{1}{(x - 3)^{\frac{1}{3}}}, which diverges as x3x \to 3, the integral diverges.

Thus, the given integral does not have a finite value.


Would you like more detailed steps on testing convergence or exploring other similar integrals? Here are some related questions for you to explore further:

  1. How do we determine if an improper integral converges or diverges at a singularity?
  2. What is the behavior of integrals involving fractional exponents near singular points?
  3. Can we apply any substitution to simplify the evaluation of improper integrals?
  4. What are some examples of integrals that are "conditionally convergent" despite having singularities?
  5. How can we approximate the value of an improper integral using numerical methods?

Tip: When dealing with improper integrals, always check for singularities and the behavior of the integrand near those points before attempting to evaluate the integral.

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Math Problem Analysis

Mathematical Concepts

Improper Integrals
Fractional Exponents
Singularities in Integrals

Formulas

∫ (x - a)^n dx = ((x - a)^(n+1)) / (n+1) + C, for n ≠ -1
Improper integral evaluation by splitting at singular points

Theorems

Divergence of Improper Integrals
Singularity Analysis in Definite Integrals

Suitable Grade Level

Undergraduate Calculus