SOLUTION: We are solving for f. The equation is 1/p + 1/q = 1/f if pg is common deminator then we would multiply each side by pg so q+p=1/f x pg. So would I then divide each side by pg s

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: We are solving for f. The equation is 1/p + 1/q = 1/f if pg is common deminator then we would multiply each side by pg so q+p=1/f x pg. So would I then divide each side by pg s      Log On


   

Question 25093: We are solving for f. The equation is
1/p + 1/q = 1/f
if pg is common deminator then we would multiply each side by pg so
q+p=1/f x pg. So would I then divide each side by pg
so I would get q+p/pq=1/f. The answer in the book is
f=pq/p+q which is the opposite of what I got. Thanks for your help.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve:
1%2Fp+%2B+1%2Fq+=+1%2Ff Add the fractions on the left sides. Common denominator is pq.
1) %28p%2Bq%29%2Fpq+=+1%2Ff Multiply both sides by pq.
2) %28p%2Bq%29+=+pq%2Ff Multiply both sides by f.
3) f%28p%2Bq%29+=+pq Finally, divide both sides by (p+q)
4) f+=+pq%2F%28p%2Bq%29
Notice that you could have just inverted equation 1) to arrive at the same conclusion.