# integral 2/sqrt(x^2-4)

• February 28th 2010, 09:06 PM
cmm1863
integral 2/sqrt(x^2-4)
i keep getting 2ln|(x/2)-(sqrt(x^2-4)/2)|+c but the the correct answer isnt divided by two inside the ln.
• February 28th 2010, 10:09 PM
CaptainBlack
Quote:

Originally Posted by cmm1863
i keep getting 2ln|(x/2)-(sqrt(x^2-4)/2)|+c but the the correct answer isnt divided by two inside the ln.

See what WolframAlpha does (though you may want to put absolute values in the logs):

http://www.mathhelpforum.com/math-he...1&d=1267423722
• February 28th 2010, 10:13 PM
CaptainBlack
Quote:

Originally Posted by cmm1863
i keep getting 2ln|(x/2)-(sqrt(x^2-4)/2)|+c but the the correct answer isnt divided by two inside the ln.

You can multiply inside the log by whatever you want, it results in a different additive constant at the end:

$\ln(k f(x))=\ln(f(x))+\ln(k)$

CB