Hi, i'm a very beginner to mathematica, and i know practically nothing of it, so sorry if these are stupid questions.
1) how can i plot a function like f[x]:= (x^2 + r^2)/2rx , where x is the unknown, and r is a constant on which i can do some assumptions like r>0 ^ r<10, or simply r>0 ?
2) what are the basic commands to solve inequalities? (for example (x^2 + 3)/x^3 - 20 > 0 : what's the command to find the intervals of x values where inequality is true?).