How can I effectively use substitution to evaluate this integral?

In summary, to evaluate the integral Int((x+5)(x-5)^(1/3)dx, the recommended substitution is u=x-5. This results in the integral (u+10)(u)^(1/3) du, which can be simplified by expanding the u^(1/3) into both terms and then easily integrated.
  • #1
htoor9
17
0

Homework Statement



Evaluate the integral.

Int((x+5)(x-5)^(1/3)dx

Homework Equations


The Attempt at a Solution



I've attempted the problem but subsitution doesn't seem to do anything, as du = dx if u = x-5, which doesn't cancel anything.
 
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  • #2
That's exactly the substitution you want to go with. If [itex]u=x-5[/itex] then [itex]x=u+5[/itex], which you can use in the other factor in the integrand.
 
  • #3
Tom Mattson said:
That's exactly the substitution you want to go with. If [itex]u=x-5[/itex] then [itex]x=u+5[/itex], which you can use in the other factor in the integrand.

So then what? I have integral of (u+10)(u)^(1/3) du.
 
  • #4
htoor9 said:
So then what? I have integral of (u+10)(u)^(1/3) du.

Expand the u^(1/3) into both terms. It should be easy to integrate then.
 

1. What is an integral substitution problem?

An integral substitution problem is a type of integration problem in calculus where a change of variables is used to simplify the original integral. This technique is particularly useful for solving integrals that involve complicated functions or expressions.

2. How is integral substitution different from traditional integration methods?

Integral substitution uses a change of variables to simplify the integral, whereas traditional integration methods such as integration by parts or the power rule involve applying specific rules or formulas to solve the integral.

3. What are the steps for solving an integral substitution problem?

The steps for solving an integral substitution problem are as follows:

  1. Identify a suitable substitution that will simplify the integral.
  2. Make the necessary substitutions in the original integral, including the limits of integration.
  3. Simplify the integral using algebraic manipulation to eliminate the original variable.
  4. Integrate the simplified integral using traditional integration methods.
  5. Substitute the original variable back into the final answer.

4. What are some common trigonometric substitutions used in integral substitution problems?

Some common trigonometric substitutions used in integral substitution problems include:

  • sinθ = √(1 - cos²θ)
  • tanθ = √(sec²θ - 1)
  • secθ = √(tan²θ + 1)
These substitutions are particularly useful for integrals involving trigonometric functions such as sine, cosine, tangent, secant, or cosecant.

5. What are some applications of integral substitution in real-world problems?

Integral substitution has many applications in real-world problems, particularly in physics and engineering. It can be used to solve problems involving position, velocity, acceleration, and force, as well as in calculating areas, volumes, and probabilities. It is also used in fields such as economics, chemistry, and biology to model and analyze various systems and processes.

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