Confused with solve function.

I'm confused with the solve function. I used it this way before, can't find the issue here. Why it's not solving?

Answer 1

[Star Strider]

This (typed in laboriously because you posted an image of your code rather than the code itself):

syms s X(s) Y(s) U(s) 
TF_XU = (s^2 + 3*s + 5)*X(s) == (s^2 + s)*U(s) + (2*s^2 + 4*s)*Y(s);
TF = isolate(TF_XU,X)

produces:

TF =
X(s) == (Y(s)*(2*s^2 + 4*s) + U(s)*(s^2 + s))/(s^2 + 3*s + 5)

This is likely as close as you can get.