Posted by PLEASE HELP!! on .
The rule for multplying and dividing both sides of an inequality do not meantion zero. Explain why??

Math 
MathMate,
In general, we do not multiply or divide each side of an equality by zero, as it could give erroneous results. So the same applies to inequalities.
For example:
A=B
Multiply by A:
A*A = A*B
Subtract B²:
A²B² = AB  B²
Factor each side:
(A+B)(AB) = B(AB)
Cancel out (AB)
A+B = B
How does the fallacy work: we divided each side by (AB) which is zero!