Integrating S(x(x+1)1/2) dx: A Step-by-Step Guide

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In summary, the integral of √(x+1) times an ordinary polynomial in x is equal to (2/5)(x+1)^(5/2)-(2/3)(x+1)^(3/2) + C. There was an error in the simplification process, but it has been corrected.
  • #1
tjohn101
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Homework Statement


S(x(x+1)1/2) dx

Homework Equations


The Attempt at a Solution


u=x+1
du=1
x=u-1

S(x(u)1/2) du

S(((u-1)(u)1/2) du

S((u2-u)1/2) du

S(u-u1/2) du

S((1/2)u2-(2/3)u3/2)

=(1/2)(x+1)2-(2/3)(x+1)3/2) + COnline homework says it's wrong... Where did I mess up?
 
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  • #2
Hi tjohn101! :smile:

(have an integral: ∫ :wink:)
tjohn101 said:
S(((u-1)(u)1/2) du

S((u2-u)1/2) du

S(u-u1/2) du

Neither of these lines is correct. :redface:

(u-1)√u = u√u - √u :wink:
 
  • #3
Ahhhh thank you. I didn't notice I had done that :/
 
  • #4
Hmmm I ended up getting

(2/5)(x+1)5/2-(2/3)(x+1)3/2 + C

Sound right?
 
  • #5
Hi tjohn101! :smile:

(just got up :zzz: …)

Yes :smile:but perhaps you should put it in the same form as the question, ie √(x+1) times an ordinary polynomial in x ? :wink:
 
  • #6
Thank you for your help!
 

1. What is integration and why is it important?

Integration is a mathematical process of finding the area under a curve. It is important because it allows us to calculate values such as displacement, velocity, and acceleration in physics, and also plays a crucial role in solving real-world problems in fields such as economics, engineering, and biology.

2. What are the different methods of integration?

The most commonly used methods of integration are the integration by substitution, integration by parts, and integration using partial fractions. Other methods include trigonometric substitution, integrals involving logarithmic and exponential functions, and numerical integration using techniques such as the trapezoidal rule and Simpson's rule.

3. How do I know which method of integration to use?

Choosing the right method of integration depends on the type and complexity of the problem. Generally, it is helpful to first try substitution or integration by parts. If those methods do not work, then you can try other techniques such as partial fractions or trigonometric substitution. Practice and experience can also help in determining the most efficient method for a given problem.

4. Can integrals be solved without using formulas?

Yes, integrals can be solved without using formulas, but it may require more complex techniques such as numerical integration. These methods involve dividing the area under the curve into smaller sections and approximating the area using mathematical formulas. While this may be more time-consuming, it can be a useful approach when dealing with functions that do not have simple integration formulas.

5. How can I check if my integration is correct?

One way to check if your integration is correct is by differentiating the result and seeing if it returns the original function. This is known as the "reverse chain rule". Another method is to use online integration calculators or software, which can provide a step-by-step solution and can also graph the result for visual confirmation. It is always a good idea to double-check your work using multiple methods to ensure accuracy.

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