You have a calculator whose multiplication button is broken. The only operations that work are addition (x+y), subtraction (x-y), and reciprocation (1/x).

Can you use this calculator to multiply two numbers?

I just want to make sure I understand how this calculator works.

For example, I am sure I can do the following without any confusion:
(x+y)^-1 = 1/(x+y)
The sequence of "key strokes" would be x, +, y, inv.

But can I do this?
x^-1 + y^-1 = 1/x+1/y = (x+y)/(xy)
The sequnce of keystrokes would be x, inv, +, y, inv.
Or would that give me (x^-1 + y)^-1 = x/(xy+1)

See my confusion?

Posted by nikki on 2005-01-20 20:32:08