Expert: Paul Klarreich - 6/16/2008

Question
i'm taking a semester of college algebra and i need help with getting started on this problem.

solve the following formula for the specified variable.

1/f=1/p+1/q ; f

thanks!

Answer
Questioner:   angel
Category:  Advanced Math
Private:  No
 
Subject:  solving formulas
Question:  i'm taking a semester of college algebra and i need help with getting started on this problem.

solve the following formula for the specified variable.

1/f=1/p+1/q ; f

thanks!

........................................
Hi, Angel,

1/f = 1/p + 1/q


To solve:
1
--- = something
f

for f, you should invert both sides:
       1
f = ----------
   something

In this case, the 'something' is:

1/p + 1/q

so you have

      1
f = ----------
   1/p + 1/q

which is an answer, of sorts.  If you want to simplify the right side, multiply each term by the l.c.d. = pq:


       (1)pq
f = -----------------
   pq(1/p) + pq(1/q)


     pq
f = ------
    q + p

No doubt you got this formula from your book on electric circuit theory, right?