posted by confused....

If a * b = a - 3b and a # b = 2a + 3b, evaluate the expression (4 * 3) # 5.

If y # y = 2x + 3y and x * y = 5x + 4y, evaluate the expression 2 # (4 * 3).

Please help! Try to explain how I should solve these - don't just give me the answer. These problems showed up in my math book, and my teacher didn't teach us how to do those in the lesson. And, first of all, what does # mean in a problem like this? Thank you.

1. bobpursley

4*3=4-3*3=-5 according to the rules.
-5#5= 2*-5 + 3*5 or 5 according to the rules.

# is the symbol for an unknown math operator, defined as a#b=2a + 3b

2. confused...

hmm...interesting. sorry to say, I still don't get this! thank you for your help, though, Bob.

my math teacher ending up explaining this today (after he took a homework completion grade - of course I hadn't been able to do the problem!)and then I just checked and read your explanation, and I still don't get it. can somebody please help?

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