(1/x) + (1/y) = (1/f). What is x(y)?

Show me how to get the answer as well please =)

Question

(1/x) + (1/y) = (1/f). What is x(y)?

Show me how to get the answer as well please =)

anonymous · Answer

anonymous · Answer

Guess and check is the best method for this, because you can't solve for three variables in one equation. 0 is one answer that works.

anonymous · Answer

I don't really need the answer, but more like an equation. There are 10 options which use the variables f, fy, and y, all in different forms.

phi · Answer

You could add 1/x + 1/y to get (x+y)/xy 
and then solve for xy

anonymous · Answer

one answer is 
$$xy=xf+yf$$

anonymous · Answer

Isolate the 1/x term, then invert both sides:
$$1/x = 1/f - 1/y$$
$$x = 1/(1/f - 1/y)$$