# If in Ring, evaluate (a+b)(c+d)

1. Homework Statement

If a,b,c,d $$\in$$ R, evaluate (a+b)(c+d). (R is a ring.

2. Homework Equations

3. The Attempt at a Solution

I think that it's simple foiling, but I'm not sure.

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Why would you suspect this not to be true?

If you're in doubt re-check the defintion of a ring.

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I doubt it simply because I'm in a 4000 level Math course. It can't be this easy an answer.

Dick
Homework Helper
What else could it be?

Well, if there's no more information about a,b,c,d than I don't know what else you could do Okay, so I'm going to guess that everyone agrees with me that this is right? It just seems too easy! Oh well, I'll accept it and move on. :-D

Treat (a+d) as one element and use the distributive property of rings. Then use it again. Make sure you keep the ordering if you're not dealing with a commutative ring.

Okay, that makes sense, PingPong! So, technically, the order is different.

(a+b)(c+d)
=> (a+b)c+(a+b)d