�Note In order to quicken this method, we can proceed as follows: After
performing steps 1, and 2, there is no need of step 3 Here, the integral will be kept
in the new variable itself, and the limits of the integral will accordingly be changed,
so that we can perform the last step Let us illustrate this by examples Example 28 Evaluate 
1
4
5
15
1
x
x
dx
−
+
∫