# Help manipulating equation!

1. Jun 3, 2010

### razmataz

I need help gettin from

(n-1)((1/r1^3)-(1/r2^3))(y^4/8) = (y^4/32f^3)

r1 and r2 have the 1 and 2 and subscript and are not numbers.

Question states r1 = f

Supposed to end up with

r2 = ((4n-4)/(4n-5))^(1/3)) * f

Can any one show me the steps?!

2. Jun 3, 2010

### Staff: Mentor

Since y4 appears on both sides, you can eliminate it by dividing both sides by y4 (and assuming that y $\neq$ 0).

Then, combine the two fractions in r1 and r2 on the left side.
Then, replace r1 by f.

Then expand everything on the left side. After that, isolate all terms that involve r2 and divide both sides by the coefficient of r2.