Solving a Complicated Integral: Exploring Substitution Method

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In summary, the integral of (5x-x^2)^2/2 can be simplified to 1/10x^5 - 5/4x^4 + 25/6x^3. The solution was found using the substitution method and the expanded form of (x-y)^2. Thanks to the contributors for their assistance.
  • #1
Ocis
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Integrate [tex]\int[/tex] [tex]\frac{\left(5x - x^{2}\right)^{2}}{2}[/tex]

I have been going round in circles using the substitution of u = [tex]\left(5x - x^{2}\right)[/tex]

But it gets too complicated, where am I going wrong? I would really appreciate it if someone could please explain in stages what exactly I have to do.
Many thanks
 
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  • #2
[tex]\frac 1 2\int(5x-x^2)^2dx[/tex]

Don't forget your dx.

Expand ... [tex](x-y)^2=x^2-2xy+y^2[/tex]
 
Last edited:
  • #3
Is the solution anywhere close to this?

[tex]\frac{\left(25x ^{3}\right)}{6}[/tex] [tex]-[/tex] [tex]\frac{\left(10x ^{4}\right)}{4}[/tex] [tex]+[/tex] [tex]\frac{\left(x ^{5}\right)}{5}[/tex]

Thanks,
 
  • #5
Oh yeah of course it is, thanks to you all. Panic over!
 

1. How do I know what method to use for solving an integral?

There are several methods for solving integrals, such as substitution, integration by parts, and trigonometric substitution. The best way to determine which method to use is by looking at the form of the integral and trying to identify patterns or similarities with integrals you have solved before.

2. What is the difference between definite and indefinite integrals?

A definite integral has specific limits of integration, while an indefinite integral does not. This means that a definite integral will give you a specific numerical value, while an indefinite integral will give you a general antiderivative.

3. How do I know if an integral is solvable?

Not all integrals can be solved analytically. Some integrals have no known closed form solution and can only be approximated using numerical methods. However, most integrals encountered in basic calculus courses can be solved using standard techniques.

4. Can I use a calculator to solve integrals?

While some calculators have the ability to evaluate simple integrals, it is important to understand the concepts and techniques behind solving integrals by hand. Additionally, calculators may not always give accurate results and should not be relied upon for solving more complex integrals.

5. Should I simplify the integrand before attempting to solve the integral?

In most cases, it is helpful to simplify the integrand as much as possible before attempting to solve the integral. This can make the problem more manageable and may reveal patterns that can help in choosing the appropriate method for solving the integral.

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