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Mathematics 18 Online
OpenStudy (anonymous):

∫dx/x^2 - 4

OpenStudy (loser66):

x^2 -4= (x+2)(x-2) then partial fraction to take integral

OpenStudy (anonymous):

Loser66....shud we then bring it to the numerator??

OpenStudy (loser66):

sure

OpenStudy (anonymous):

but then wont it hav power -1....so we cant use the formula int x^n=x^n+1/n+1

OpenStudy (loser66):

nope, you misunderstand my suggestion. let integral symbol aside. the integrand is \[\frac{1}{(x+2)(x-2)}= \frac{A}{x+2}+\frac{B}{x-2} solve ~for~ A ~and~B, \] then plug back to the integral to calculate It's called integral by partial fraction method

OpenStudy (loser66):

someone helps me explain him, please

OpenStudy (loser66):

I don't know, I don't calculate it, just give you the method.

sam (.sam.):

The answer is not ln|x+2|+ln|x-2|+c, that is just an example by cambrige

OpenStudy (loser66):

@cambrige Sorry, I don't understand what you wrote "sum1 tell if I'm r8". English is not my native language.

OpenStudy (anonymous):

*meant

OpenStudy (loser66):

to me, the answer is \[\frac{-1}{4}ln (x+2) +\frac{1}{4}ln(x-2)+ C\]

OpenStudy (anonymous):

The answer in my book is 1/4ln[x-2/x+2]+c

OpenStudy (loser66):

the same, just another way to write ln

OpenStudy (anonymous):

Thanks a lot

OpenStudy (anonymous):

so I shud delete all the comments??

sam (.sam.):

@cambrige No you need not to

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