boolean algebra rules again

[Simon]

So my BTEC L3 couse has an excersise I need to demonstrate with karnaugh maps the following:

1) A+AxB = A

Well A+A = A

so it's now AxB=A

Is it is me or this cannot be because A AND B = A has nothing to do with the AND truth table and it will depend on B as well not just A.

[electr_peter]

I suggest to change "+" --> "OR" and "*" --> "AND".
A+AxB = A --> A OR (A AND B) = A. Now go from there.

[Simon]

so I have to fulfill the AND operation first ?

[electr_peter]

In this context, "AND" operation should be completed first, because it is same as "*" operation in first equation. "*"has higher priority than "+" operation and it implies brackets around A*B.

"AND" and "OR" are not the same as "*" and "+" in all contexts. Brackets "override" order of logical operations and make it easier to visualise.

[Zero999]

Yes, AND has a higher precedence than OR, just like in normal algebra division and multiplication are performed before addition or subtraction.
http://www.asic-world.com/digital/boolean1.html
http://en.wikipedia.org/wiki/Logical_connective#Order_of_precedence

[Simon]

yep something else the course material kindly forgot to mention