Solving the Antiderivative of sqrt(1-(x^2/2))

In summary, the antiderivative of \sqrt{1-\frac{x^2}{2}} can be computed by substituting x=\sqrt{2} \sin u and using the Riemann measure on \mathbb{R} : dx. The integrand \int\log|\sqrt{1-x^2}+x| is related to an inverse hyperbolic trig function and cannot be expressed algebraically using elementary functions. However, it can be calculated using software such as Mathematica.
  • #1
Icebreaker
[SOLVED] Simple Antiderivative

How would I compute the antiderivative of

[tex]\int \sqrt{1-\frac{x^2}{2}}[/tex]

It looks familiar, but I can't quite remember how...
 
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  • #2
Put

[tex]x=\sqrt{2} \sin u[/tex]

and go from there.
 
  • #3
U can also put the Riemann measure on [itex]\mathbb{R} [/itex] : [itex] dx [/itex]. :wink:

Daniel.
 
  • #4
Ah yes, of course. Thanks.

Quick follow-up:

[tex]\int\log|\sqrt{1-x^2}+x|[/tex]
 
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  • #5
I think that integrand is related to an inverse hyperbolic trig function... but I'd have to play around with it to work out which one. Maybe somebody else...
 
  • #6
Perhaps it simply cannot be expressed algebraically?
 
  • #7
Icebreaker said:
Perhaps it simply cannot be expressed algebraically?
It cannot be expressed in terms of elementary functions, you are correct.

I love Mathematica :smile:

Alex
 

What is an antiderivative?

An antiderivative is the inverse operation of taking a derivative. It is a function that, when differentiated, yields the original function.

Why is finding the antiderivative of sqrt(1-(x^2/2)) important?

Finding the antiderivative allows us to determine the original function that was differentiated. This is useful in a variety of mathematical applications, such as finding the area under a curve or solving differential equations.

What are the steps to solve for the antiderivative of sqrt(1-(x^2/2))?

1. Rewrite the expression as sqrt(1- (x^2/2)) = sqrt(1 - (x^2/2)^2)
2. Use the trigonometric identity sin^2(x) + cos^2(x) = 1 to rewrite the expression as sqrt(cos^2(x))
3. Apply the power rule for antiderivatives, which states that the antiderivative of x^n is (1/(n+1))x^(n+1)
4. Substitute cos(x) for x and simplify to get the final answer: (2/3)cos^3(x).

Can the antiderivative of sqrt(1-(x^2/2)) be solved without using trigonometric identities?

Yes, the antiderivative can also be solved using a substitution method. Let u = 1 - (x^2/2), then the expression becomes sqrt(u). Using the power rule for antiderivatives, the final answer would be (2/3)(1 - (x^2/2))^(3/2) + C.

Are there any other methods for solving the antiderivative of sqrt(1-(x^2/2))?

Yes, there are other methods such as integration by parts or using the trigonometric substitution method. These methods may be more complex, but they can also be used to solve the antiderivative of sqrt(1-(x^2/2)).

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