# Revision history [back]

### Substitution

After some calculation I arrive to the following equation $\frac{Dp - D+ I}{D(P-1)}$. Whichever be the command I use I cannot put it as $\frac{D(p - 1)+ I}{D(P-1)}$ or as $1-\frac{I}{D*(P-1)}$ or $1-\frac{I}{D}\frac{1}{(P-1)}$. This last equation is the one of interest since I would like to solve $1-\frac{I}{D}\frac{1}{(P-1)}==0$ according to $\frac{D}{I}$. Is there a way to use solve() acording to $\frac{D}{I}$ ? I have tried to substitue x with a form of substitute()for it, but it was an echec. I understand that substitue a ratio of 2 variables for one is a little bit complex.

 2 None FrédéricC 5114 ●3 ●42 ●111

### Substitution

After some calculation I arrive to the following equation $\frac{Dp - D+ I}{D(P-1)}$. Whichever be the command I use I cannot put it as $\frac{D(p - 1)+ I}{D(P-1)}$ or as $1-\frac{I}{D*(P-1)}$ or $1-\frac{I}{D}\frac{1}{(P-1)}$. This last equation is the one of interest since I would like to solve $1-\frac{I}{D}\frac{1}{(P-1)}==0$ according to $\frac{D}{I}$. Is there a way to use solve() acording to $\frac{D}{I}$ ? I have tried to substitue x with a form of substitute()for it, but it was an echec. I understand that substitue a ratio of 2 variables for one is a little bit complex.

 3 None tmonteil 27283 ●31 ●201 ●514 http://wiki.sagemath.o...