These are enough values to give several co-ordinates to plot on a graph so
you can see what the function is doing. If I picked just x values
1, 2, 3, 4, 5 then I might not realize that this
function soars off to (positive) infinity as I get closer to zero on the
positive side. The function is very close to zero and negative when I
give it a large negative value of x. There's a vertical asymptote at x=0 - the
value for which the function isn't defined.
Tables of values are pretty good tools for giving you a rough sketch,
but if you don't choose good values of x, you might miss important details,
so it's not a rigourous understanding of the function, but it is a good
technique for getting oriented on a function and for double-checking later.
Hope this helps!
Stephen La Rocque>