# [✓] Use Assuming and Substitute commands to simplify the expression?

GROUPS:
 I used the commands Assuming and /. to simplify the expression, but they didn't work. Would you like to have a look at this issue? Thanks. In[122]:= eq1 = ( 2 A1 Dc Sqrt[Dp] E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s)/(Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Sqrt[Dp] E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp^(3/2) E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s \[Alpha]1)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dc Sqrt[Dp] s)/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^(3/2) Sqrt[ s + \[Theta]c])/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Sqrt[Dc] Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s Sqrt[ s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^2 \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dp^2 E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp^(3/2) pinf s \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp pinf Sqrt[s] (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp^(3/2) pinf \[Alpha]1 (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 Sqrt[Dp^3 s^5 (s + \[Theta]c)])/( Sqrt[s] Sqrt[s/ Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 \[Theta]c (2 s + \[Theta]c))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp Sqrt[ s] (-pinf s^2 + A2 Sqrt[Dp s] \[Alpha]1 - pinf s \[Theta]c))/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) (2 s^3 - Sqrt[Dp s^5] \[Alpha]1 + 2 s^2 \[Theta]c))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 (A2 s Sqrt[Dp s] Sqrt[s + \[Theta]c] - pinf Sqrt[Dp s^5 (s + \[Theta]c)]))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) Out[122]= ( 2 A1 Dc Sqrt[Dp] E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Sqrt[Dp] E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp^(3/2) E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s \[Alpha]1)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dc Sqrt[Dp] s)/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^(3/2) Sqrt[ s + \[Theta]c])/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Sqrt[Dc] Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^2 \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dp^2 E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp^(3/2) pinf s \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp pinf Sqrt[s] (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp^(3/2) pinf \[Alpha]1 (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 Sqrt[ Dp^3 s^5 (s + \[Theta]c)])/( Sqrt[s] Sqrt[s/ Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 \[Theta]c (2 s + \[Theta]c))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp Sqrt[ s] (-pinf s^2 + A2 Sqrt[Dp s] \[Alpha]1 - pinf s \[Theta]c))/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) (2 s^3 - Sqrt[Dp s^5] \[Alpha]1 + 2 s^2 \[Theta]c))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 (A2 s Sqrt[Dp s] Sqrt[s + \[Theta]c] - pinf Sqrt[Dp s^5 (s + \[Theta]c)]))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) In[123]:= eq2 = Assuming[s > 0 && (s + \[Theta]c) > 0 && Dp > 0, Cancel[eq1]] /. {Sqrt[Dp s] -> Sqrt[Dp] Sqrt[ s], Sqrt[Dp s (s + \[Theta]c)] -> Sqrt[Dp ] Sqrt[ s ] Sqrt[s + \[Theta]c], Sqrt[s/Dp] -> Sqrt[s]/Sqrt[Dp]} Out[123]= ( 2 A1 Dc Sqrt[Dp] E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Sqrt[Dp] E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp^(3/2) E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s \[Alpha]1)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dc Sqrt[Dp] s)/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^(3/2) Sqrt[ s + \[Theta]c])/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Sqrt[Dc] Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^2 \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dp^2 E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp^(3/2) pinf s \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp pinf Sqrt[s] (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp^(3/2) pinf \[Alpha]1 (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 Sqrt[ Dp^3 s^5 (s + \[Theta]c)])/( Sqrt[s] Sqrt[s/ Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 \[Theta]c (2 s + \[Theta]c))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp Sqrt[ s] (-pinf s^2 + A2 Sqrt[Dp] Sqrt[s] \[Alpha]1 - pinf s \[Theta]c))/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) (2 s^3 - Sqrt[Dp s^5] \[Alpha]1 + 2 s^2 \[Theta]c))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 (A2 Sqrt[Dp] s^(3/2) Sqrt[s + \[Theta]c] - pinf Sqrt[Dp s^5 (s + \[Theta]c)]))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) 
9 months ago
4 Replies
 Neil Singer 2 Votes Assuming does not do anything unless you put a Simplify or Reduce or Integration inside of it. The form should be Assuming[a>0, Simplify[expression]] Regards
 I tried but there is no change. Thanks for your tips. In[125]:= eq43 = Assuming[s > 0 && (s + \[Theta]c) > 0, Cancel[eq42]] Out[125]= ( 2 A1 Dc Sqrt[Dp] E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Sqrt[Dp] E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ s + \[Theta]c] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp^(3/2) E^((lh Sqrt[s + \[Theta]c])/Sqrt[Dc] - (x Sqrt[s + \[Theta]c])/ Sqrt[Dc]) s \[Alpha]1)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dc Sqrt[Dp] s)/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf s \[Alpha]1 \[Theta]c)/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^(3/2) Sqrt[ s + \[Theta]c])/((Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A1 Sqrt[Dc] Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) s Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A2 Dp^2 \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( A2 Dp^2 E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp^(3/2) pinf s \[Alpha]1 Sqrt[s + \[Theta]c])/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp pinf Sqrt[s] (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dp^(3/2) pinf \[Alpha]1 (s + \[Theta]c)^(3/2))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 Sqrt[ Dp^3 s^5 (s + \[Theta]c)])/( Sqrt[s] Sqrt[s/ Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dp^(3/2) E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[Dp]) pinf \[Alpha]1 \[Theta]c (2 s + \[Theta]c))/( Sqrt[s/Dp] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) + ( Dc Dp Sqrt[ s] (-pinf s^2 + A2 Sqrt[Dp s] \[Alpha]1 - pinf s \[Theta]c))/( Sqrt[Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) Sqrt[s + \[Theta]c] Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( A1 Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) (2 s^3 - Sqrt[Dp s^5] \[Alpha]1 + 2 s^2 \[Theta]c))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) - ( Dc Dp E^((lh Sqrt[s])/Sqrt[Dp] - (Sqrt[s] x)/Sqrt[ Dp]) \[Alpha]1 (A2 s Sqrt[Dp s] Sqrt[s + \[Theta]c] - pinf Sqrt[Dp s^5 (s + \[Theta]c)]))/( Sqrt[s] Sqrt[ Dp s] (Sqrt[s] + Sqrt[Dp] \[Alpha]1) (s + \[Theta]c) Sqrt[ Dp s (s + \[Theta]c)] (-Dc s + Dp s + Dp \[Theta]c)) 
 Neil Singer 1 Vote It worked for me. Your example does not have a Simplify in it. Cancel[] does not use Assuming. Assuming[s > 0 && (s + \[Theta]c) > 0 && Dp > 0, Simplify[eq1]] /. {Sqrt[Dp s] -> Sqrt[Dp] Sqrt[s], Sqrt[Dp s (s + \[Theta]c)] -> Sqrt[Dp] Sqrt[s] Sqrt[s + \[Theta]c], Sqrt[s/Dp] -> Sqrt[s]/Sqrt[Dp]} 
 Bill Simpson 1 Vote An alternative method.Look at FullForm[eq1] and find the exact form your expression appears in. This may be different from the displayed form, particularly when there are denominators or negative exponents. Copy the exact form from the FullForm into your replacement pattern like these which I found in your eq1: eq2 = eq1 /. {Power[Times[Dp, s], Rational[-1, 2]] -> 1/(Sqrt[Dp]*Sqrt[s]), Power[Times[Dp, s, Plus[s, \[Theta]c]], Rational[-1, 2]] -> 1/(Sqrt[Dp] Sqrt[s] Sqrt[s + \[Theta]c]), Power[Times[Power[Dp, -1], s], Rational[-1, 2]] -> 1/(Sqrt[s]/Sqrt[Dp])} The precise format of the right hand side of each replacement rule is not as critical as the left hand side.This method often takes more work, but will sometimes succeed when trying again and again to find a way to make the substitution work has failed.After the substitution there may be automatic changes to the format before it is displayed. It is even possible that the automatic changes may undo your some or all of your substitutions, like if you wanted to substitute 7*7 for 49 or x*x for x squared or other less obvious things.