Question

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

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

Answer 1

http://www.wolframalpha.com/input/?i=%281%2Fx%29+%2B+%281%2Fy%29+%3D+%281%2Ff%29

Answer 2

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.

Answer 3

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.

Answer 4

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

Answer 5

one answer is
\[xy=xf+yf\]

Answer 6

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