In [1]: ex = sqrt(x+1)+x+3
In [2]: ex.subs(x, solve(y-sqrt(x+1), x)[0])
Out[2]:
____
2 ╱ 2
y + ╲╱ y + 2
If *y* is declared to be positive, you get the right expression.
On Wednesday, April 1, 2015 at 7:01:29 PM UTC+2, Paul Royik wrote:
>
> Is there a function that will convert sqrt(x+1)+x+3 into y^2+y+2 with
> y=sqrt(x+1)?
> Subs is smart enough to make (x**4+x**2+2).subs(x**2, y) into y**2+y+2.
>
> But it doesn't work with initial example. Even sqrt(x+1)+x+1 is not
> converted into y^2+y
>
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