Dimana kesalahan anda ??????

Carilah dimana letak kesalahan anda !
Diket : a = b
Maka : 
a = b
a x a = b x b
a2 – b2 = ab – b2 
( a+b )( a – b ) = ( a – b ) b
( a+b ) = b
( a+a ) = a
2a = a
2 = 1
............................???????
Benarkah Jawaban anda????