Thursday, March 31, 2011

`int dx / sqrt(1-(x+1)^2)` Find the indefinite integral

Indefinite integral are written in the form of `int f(x) dx = F(x) +C`


 where: f(x) as the integrand


           F(x) as the anti-derivative function 


           C  as the arbitrary constant known as constant of integration



For the given problem, the integrand `f(x) =1/sqrt(1 -(x+1)^2)`  we apply


u-substitution by letting `u =(x+1) `  and `du = 1 dx or du= dx` .


`int (dx)/sqrt(1 -(x+1)^2) = int (du)/sqrt(1 -u^2)`



`int (du)/sqrt(1 -u^2) `  resembles the basic integration` ` formula for inverse sine function: `int (dx)/sqrt(1-x^2)=arcsin(x) +C` .


By applying the formula, we get:


`int (du)/sqrt(1 -u^2) =arcsin(u) +C`


Then to express it in terms of x, we substitute `u=(x+1)` :


`arcsin(u) +C =arcsin(x+1) +C`

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