Wednesday, September 25, 2013

evaluate ((lnx)^2)^ 1/2 dx

I suppose that you need to find the integral of the
function `sqrt((lnx)^2) `  such that:


`int sqrt((lnx)^2)
dx`


You need to remember that `sqrt(x^2) = |x|, `  hence
`sqrt((lnx)^2) = |ln x|`


`` `int sqrt((lnx)^2) dx = int |ln
x| dx`


You need to use integration by parts, hence you
should write the formula such that:


`int udv = uv - int
vdu`


You should consider `u = ln x =gt du = (dx)/x` ,
hence`dv = dx =gt v = x` Substituting `ln x`  for u, `(dx)/x`  for du, x for v and dx
for dv yields:


int |ln x| dx = x*|ln x| - int
x*(dx)/x


`int |ln x| dx = x*|ln x| - int
dx`


`int |ln x| dx = x*|ln x| - x + c =gt int |ln x| dx =
x*(|ln x| - 1) + ` c


`int |ln x| dx = x*(|ln x| - ln e) +
c`


`int |ln x| dx = x*|ln(x/e)| +
c`


Hence, evaluating the integral of function
yields `int sqrt((lnx)^2) dx = x*|ln(x/e)| + c` .

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