I am trying to understand how assumptions and simplification works with this simple example:
x+y=5, assume x = 2y
So I write:
Assuming[x == 2y, Simplify[x+y==5]]
And the result makes sense to me:
3y == 5
But then if want to do
x+y=5, assume y = 2x
and I write:
Assuming[y == 2x, Simplify[x+y==5]]
when I should be getting:
Update: I know this works:
Simplify[x + y == 5] /. y -> 2 x what I want to understand is why Assuming does what it does: Am I using it wrong somehow?
I now tried:
Assuming[q == 2 p, Simplify[p + q == 5]] vs
Assuming[p == 2 q, Simplify[p + q == 5]] same issue, I am starting to wonder if it has something to do with alphabetical order of the name of the variables.