Sketch a graph of f
(
x
)
=
⎧
⎪
⎨
⎪
⎩
−
1
if
x
≤
−
1
2
x
+
1
if
−
1
<
x
≤
2
3
if
x
>
2

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.