1.

A

=

B

Given

2.

A2

=

AB

Multiply by A (MPE)

3.

A2 B2

=

AB B2

Subtract B2  (APE)

4.

(A + B)(A B)

=

B(A B)

Factor both sides

5.

A + B

=

B

Cancel common factors

6.

B + B

=

B

Substitution (using step 1)

7.

2B

=

B

Simplification

8.

2

=

1

Cancel common factor.