Question

How do you write a specific formula to describe the variation: S varies jointly with the inverse of the square of P and inversely with the cube of L; S=6 when P=8, L=10?

Answer 1

Variation equation is `S = 384000 * 1/(P^2*L^3)`

Explanation:

`S prop 1/P^2 and S prop 1/L^3` When varies jointly,

`S prop 1/(P^2*L^3) or S = k * 1/(P^2*L^3) :. k = S*P^2*L^3` "k" is a constant.

`S=6 , P=8 , L=10 :. k= 6*8^2*10^3 = 384000`

So variation equation is `S = 384000 * 1/(P^2*L^3)` [Ans]