How Do I Compute the Integral Using u-Substitution?

If you substitute u = x - 4, the integral becomes (2u + 9)/u^6, which is much easier to integrate than the original expression. In summary, the conversation discusses the best method to use when faced with a tedious partial fraction expansion, with one person suggesting an ordinary substitution and another acknowledging its efficiency in simplifying the integral.
  • #1
kyu
12
0


what method should i use? i tried

u = x - 4
du = dx

i can't continue. enlighten me please
 

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  • #2
It looks like a pretty tedious partial fraction expansion.
 
  • #3
kyu said:
what method should i use? i tried

u = x - 4
du = dx

i can't continue. enlighten me please
That works. Keep in mind that if u = x -4, then x = u + 4. Replace x and dx in the integral with what you have for u and du, and you'll get an integral that's easy to work with.

Zondrina said:
It looks like a pretty tedious partial fraction expansion.
An ordinary substitution will do the trick.
 
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  • #4
Zondrina said:
It looks like a pretty tedious partial fraction expansion.

It is neither tedious nor particularly helpful.

$$\frac{2x+1}{(x-4)^6}=\frac{2(x-4)+9}{(x-4)^6}$$
 
  • #5
lurflurf said:
It is neither tedious nor particularly helpful.

$$\frac{2x+1}{(x-4)^6}=\frac{2(x-4)+9}{(x-4)^6}$$

This is quite efficient to compute the integral. ;)
 
  • #6
NasuSama said:
This is quite efficient to compute the integral. ;)

What do you mean?
 
  • #7
NasuSama said:
This is quite efficient to compute the integral. ;)

mafagafo said:
What do you mean?

He means it is easy.
 

1. What is the difference between numerical and analytical integration?

Numerical integration involves approximating the value of an integral using numerical methods, while analytical integration involves finding the exact solution using mathematical techniques such as substitution and integration by parts.

2. What is the most commonly used method of integration?

The most commonly used method of integration is the fundamental theorem of calculus, which states that the integral of a function can be evaluated by finding its antiderivative.

3. How do you determine which method of integration to use?

The method of integration used depends on the complexity of the integrand and the techniques that are available for solving it. Some common methods include substitution, integration by parts, partial fractions, and trigonometric substitution.

4. Can you use more than one method of integration for a single integral?

Yes, it is possible to use more than one method of integration for a single integral. This is often necessary for integrands that are too complex to be solved using a single method.

5. Are there any limitations to using numerical methods of integration?

Yes, numerical methods of integration have limitations such as being prone to error and requiring a lot of computation for complex integrals. They also cannot provide exact solutions like analytical methods can.

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