1st problem is nice I will tell you the general way of solving these problems
It is the type of problems where
x m ( a + bx n ) p ,
Now here you have m = - 3 , n = 1 , p = 2
In these type of problems you have, (m+1)/n = an integer , so you can try putting
( a + b x n ) part = t k where k is the denominator of the fraction p
now replace it as said and you will see its easy ,
It now reduces to
2 t dt / t ( t2 + 1 ) = 2 dt / (t 2 + 1) 3
Now make required substitutions and get the answer.....this is the approach.
__________________________________________________________________________________________________________
From J.R.R. Tolkien's 'The Lord of the Rings':
All that is gold does not glitter
Not all who wander are lost
The old that is strong does not wither,
Deep roots are not reached by frost.
From ashes a fire shall be woken
From shadows a light shall spring
Renewed shall be blade that's broken
The crown less again shall be king.