Hi,
I'm trying to solve:
S:=157.34
b:=-0.34
N=10^6
aa:=solve(S=A*N^b,A,16000,17000)

Then, SMath give me this message: "No real roots". I found ("by hand") that the answer is A=1.69*10^4. So, what is the problem with SMath?

Hello oscampo,

It seems you are wrong. This is not a nonlinear equation on A, therefore:
[MATH]A←S/{N^b}[/MATH]
[MATH]A=17251,9879[/MATH]
If you still want to use "solve", the problem is of the numerical nature and you have to plot the function and use the range as small as possible arround the solution.
Try this:
[MATH]solve(S≡A*N^b;A;17200;17300)=17251,9879[/MATH]

Regards,
Radovan