Sunday, 16 March 2014

`int (4x-2/(2x+3)^2) dx` Find the indefinite integral

`int (4x - 2/(2x+3)^2)dx`


To solve, express it as difference of two integrals.


`= int 4x dx - int 2/(2x+3)^2dx`


Then, apply negative exponent rule `a^(-m)=1/a^m` .


`= int 4xdx - int 2(2x+3)^(-2)dx`


For the second integral, apply the u-substitution method. 



`u = 2x + 3`


`du = 2dx`



Expressing the second integral in terms of u variable, it becomes:


`=int 4xdx - int (2x+3)^(-2) * 2dx`


`=int 4xdx - int u^(-2) du`


For both...

`int (4x - 2/(2x+3)^2)dx`


To solve, express it as difference of two integrals.


`= int 4x dx - int 2/(2x+3)^2dx`


Then, apply negative exponent rule `a^(-m)=1/a^m` .


`= int 4xdx - int 2(2x+3)^(-2)dx`


For the second integral, apply the u-substitution method. 



`u = 2x + 3`


`du = 2dx`



Expressing the second integral in terms of u variable, it becomes:


`=int 4xdx - int (2x+3)^(-2) * 2dx`


`=int 4xdx - int u^(-2) du`


For both integrals, apply the formula `int x^ndx= x^(n+1)/(n+1)+C` .


`= (4x^2)/2 - u^(-1)/(-1) + C`


`=2x^2 + u^(-1) + C`


`= 2x^2 + 1/u + C`


And, substitute back `u = 2x + 3`


`=2x^2+1/(2x+3)+C`



Therefore, `int (4x - 2/(2x+3)^2)dx=2x^2+1/(2x+3)+C` .

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