hello.

i asked to proof this equation (given in the red square in the picture).

u can also see my tried in the picture i think i not correct so i need some help to understand where i wrong and how to solve it.


thanks.

 

hello
this link can help u to understand algebra
http://www.allaboutcircuits.com/vol_4/chpt_7/5.html

and this is the solution
http://im16.gulfup.com/2011-11-15/1321377440201.jpg
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and i sorry for my bad explained i don't good in expressive ..