Intersection of a 2D graph with the axis

### 3.5.6 Intersection of a 2D graph with the axis

- The ordinate of the intersection of the graph of f with the y-axis is returned by :
  `f(0)`
  indeed the point of coordinates (0,f(0)) is the intersection point of the graph of f with the y-axis,
- Finding the intersection of the graph of f with the x-axis requires to solve the equation f(x)=0.
  If the equation is polynomial-like, `solve` will find the exact values of the abscissa of these points. Input:
  `solve(f(x),x)`
  Otherwise, we can find numeric approximations of these abscissa. First look at the graph for an initial guess or a range with an intersection and refine with `fsolve`.