I was trying to explain to someone why a+b(c) is not equal to (a+b)(c). Does anybody have an idea how to convince somebody of this through common sense?

Question

anonymous · Answer

a+b(c)=a+bc

anonymous · Answer

(a+b)(c)=ac+bc

anonymous · Answer

tell him to pick a book and learn the distributive law

turingtest · Answer

I was trying to teach my Spanish teacher this concept, I doubt she wants to pick up a book about algebraic properties and memorize them.

jamesj · Answer

Use a counterexample.  

If a = b = 1, c = 2,
then
a + b(c) = 1 + 2 = 3
but
(a + b)c = 2x2 = 4

anonymous · Answer

if he's very stubborn  plug in some values and work them out!!!

turingtest · Answer

Yeah James, I did that, but all she could reply to that was "so I have to multiply first?" I don't think it gave her an intuitive understanding of the concept.

anonymous · Answer

your spanish teacher? jesus christ... are these the people teaching nowadays?

turingtest · Answer

LOL I think she was doing her daughters homework. I don't want to say she's incapable of understanding this kind of thing, but I guess it seems that way.

turingtest · Answer

oh well, I guess some people just aren't cut out for this kind of thing...

anonymous · Answer

TuringTest i need your help with another ridiculous question lol

turingtest · Answer

sure, did you post it yet?

anonymous · Answer

Yeah i did

turingtest · Answer

send me the link, yeah?

turingtest · Answer

oh I found it...

anonymous · Answer

Ok thank you