How Do You Evaluate an Integral Using Geometric Interpretation?

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SUMMARY

The integral ∫ from -2 to 2 of (x + 3)(4 - x^2)^(1/2) dx evaluates to 6π. The discussion emphasizes the importance of recognizing the geometric interpretation of the integral, which represents the area under a curve that resembles half of a circle. Participants suggest splitting the integral into two parts and using substitution techniques, including trigonometric substitution, to simplify the evaluation. The final answer is confirmed to be correct, aligning with the area calculation of the geometric figure represented by the integral.

PREREQUISITES
  • Understanding of definite integrals
  • Familiarity with geometric interpretations of integrals
  • Knowledge of substitution techniques in integration
  • Basic concepts of trigonometric substitution
NEXT STEPS
  • Study the method of trigonometric substitution in integrals
  • Learn how to interpret integrals geometrically
  • Explore the properties of definite integrals and their applications
  • Review the area formulas for circles and ellipses
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Students and educators in calculus, particularly those focusing on integral evaluation and geometric interpretations, as well as anyone seeking to improve their understanding of integration techniques.

  • #31


That depends what the answer in back of your book is.
Remember that you need the integral of 3(4-x2)1/2, not just (4-x2)1/2
 
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  • #32


The question asked to interpret it in terms of area, that's why I didnt use any integration technique e.g. substitution, but instead tried to calculate in terms of half a circle (1/2 * pi * r^2). So is the answer at the back of my book wrong?

If you had read the post you quoted in #30 you would have known that the answer in the book is correct. I suggest you go back to the very start of the problem and look at the actual integral you're trying to calculate.
 
Last edited:
  • #33


Just to sum it all up for you...

rock.freak667 said:
\int_{-2} ^{2} (x + 3)(4 - x^2)^{\frac{1}{2}} dx

Try expanding out (x+3)(4-x2)1/2, then split the integral.


(Hint: (a+b)c = ac+bc)
 

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