Mathematica doesn't evaluate roots at all.

Questions
1

It appears that Mathematica is not evaluating roots of any form at all. N[ ] does not work. It just leaves numbers such as sqrt 2 + sqrt 3. It does not even bother to evaluate something like sqrt 4. Is there a setting that I have changed that causes this, or do I need to reinstall it?

2

In[1]:= N[Sqrt[3]]

Out[1]= 1.73205

In[2]:= N[Sqrt[3], 100]

Out[2]= 1.\
7320508075688772935274463415058723669428052538103806280558069794519330\
16908800037081146186757248576
3

Mathematica requires correct syntax, and is case sensitive. It also distinguishes between exact and approximate numbers.

In[1]:= (* it returns the same to represent an exact number *)
Sqrt[3]

Out[1]= Sqrt[3]

In[2]:= (* we can ask for an approximate representation *)
N[Sqrt[3]]

Out[2]= 1.73205

In[3]:= (* or if we give it an approximate number, we get one back *)
\

Sqrt[3.]

Out[3]= 1.73205
4

You can try control-=, then “sqrt 2 + sqrt 3”, if you don’t know the proper syntax, and Mathematica will try to guess what you mean. It will show its guess as a properly formed expression, which you can accept and evaluate.