# Revision history [back]

### Solve behaviour on same equation twice

Two questions: The first one: Solving an equation:

solve(sin(x)==0,x)


gives the solution [a=pi] but

solve([sin(x)==0,sin(x)==0],x)


raises to the somehow better solution [[a == pi*z425]] Where is the difference between the two equations?

A second one: A previous version of sage 5.something could solve

solve([sin(x)==0,-sin(x)==0],x)


However Sage 6.4.1 Returns an empty list.