Combine Equations to Find Relationship Between D, F, and L

[menzo]

i have two equations:
D=AF (A is a constant)
D=BL^3 (B is a constant)
I'm trying to combining them and use a third variable to get a relationship between D F and L
I've tried AF=BL^3
A/B=(l^3)/F
but I'm stuck

 

[mfb]

You cannot solve those equations - you have three unknown variables and just two equations.

You can get a single equation where all variables appear, but how would that help? As an example, start with 2D=2BL³ and replace 2D = D+D = D+AF to get D+AF=BL³

 

[Eukonidor]

If all you want is a relationship between the three variables, you can add the two equations together and get

2D = AF + BL^3

D = (AF + BL^3)/2

You could probably graph this three-dimensionally, but you'll need a third equation to solve it definitively.