If a×b×c×d is 9, what is a+b+c+d ( a b c d are different integers)
Actually, I know the answer to this problem, (which is 1+(-1)+3+(-3)= 0), but I am not sure whether there is a systematic way to solve it.
I thought of separating the a b c and d to
a= 91/b1/c1/d b=91/a1/c1/d And so on...
However, it didn't work. Should I treat a b c d as a whole?
Edit: Sorry I am on my phone so I can't use the formattings. Thanks for your understanding
Edit: Thanks for all your help :).