Integrating sqrt(9x^2-1) Using an Integration Table - How-To Guide

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The discussion focuses on evaluating the integral of sqrt(9x^2-1) using an integration table. The initial attempts involved u-substitution, where u=9x^2-1 and du=18xdx, but the user struggled with eliminating x from the integral. A suggestion was made to apply a trigonometric substitution instead, emphasizing that the integration table likely contains the integral of the form ∫sqrt(x^2 - a^2) dx. The key step involves factoring out 9 from the radical to simplify the integral.

PREREQUISITES
  • Understanding of integral calculus concepts, specifically integration techniques.
  • Familiarity with u-substitution and trigonometric substitution methods.
  • Knowledge of integration tables and their applications in solving integrals.
  • Ability to manipulate algebraic expressions under square roots.
NEXT STEPS
  • Study the use of trigonometric substitution for integrals involving square roots, specifically ∫sqrt(x^2 - a^2) dx.
  • Review integration tables to identify common integral forms and their solutions.
  • Practice u-substitution with various integrals to gain confidence in eliminating variables.
  • Explore advanced integration techniques, including integration by parts and reduction formulas.
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Students and educators in calculus, mathematicians, and anyone seeking to deepen their understanding of integral evaluation techniques, particularly those involving square roots and integration tables.

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using integration table evaluate the following integral sqrt(9x^2-1)

I just need to know how to start this off, i tried u substitution:

u=9x^2-1 du=18xdx integral:u^(1/2)du/18x. but I don't know how to get rid of the x,

So then from there i tried to use from the integration table integral:udv = uv-(integral vdu)
u=u^1/2 dv=1/18x du=u^(3/2)/(3/2) v=
I didn't know how to go about that
 
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heighme said:
using integration table evaluate the following integral sqrt(9x^2-1)

I just need to know how to start this off, i tried u substitution:

u=9x^2-1 du=18xdx integral:u^(1/2)du/18x. but I don't know how to get rid of the x,

So then from there i tried to use from the integration table integral:udv = uv-(integral vdu)
u=u^1/2 dv=1/18x du=u^(3/2)/(3/2) v=
I didn't know how to go about that

Try a trig substitution.
 
Since you explicitly said "using integration table," a trig substitution is probably not the way to go. I'm assuming your integration table has the following integral in it:
\int \sqrt{x^2 - a^2} dx

Factor 9 out of the two terms in the radical to get 9(x^2 - 1/9).
Bring a factor of 3 out of the radical, and outside the integral.
 

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