I need some help here, this is a hard one. Show me some steps.
For the following integral
use a substitution to show that
Use these two representations of I to evaluate I.
First note what I've added in red. Sloppy notation (such as your omissions) always leads to difficulty and trouble and lost marks.
Substitute to get .
Note that is just a dummy variable in the definite integral and can be therefore replaced with any symbol, including x ....
Now add the two expressions for I to get