First do the  and get 

and put that in place of the 



Next multiply the  and get 
and put that in place of 



Now add  to both sides of the equation:



The  and the  cancel out on the left and just leave
 on the left. Replace the  by  on the right.



Add  to both sides



Replace the  on the left by .
The  and the  cancel on the right,
and you have



Divide both sides by 



The 's cancel on the right, and dividing
 by  gives 



or



Edwin