0c9b8103c6f06bf123e680e1339c70643be2b5090f411179497c3eb92e6727779c2758e1495a553b414e5029f5b94fed3c414f

A = B

A*A = A*B

A² = AB

A² - B² = AB - B²

(A+B)(A-B) = B(A-B)

A + B = B

2B = B

2 = 1

Q.E.D.