Example  1

 

 Multimedia

Graph the inequality \(y < 3x^2 -12x + 13\).


Start by graphing the corresponding function, \(y = 3x^2 - 12x + 13\). The inequality is strict, so graph the boundary with a dashed curve.



A test point can be used to determine which region to shade. Here, \((0,0)\) is used.

Left Side Right Side
\[\begin{array}{r}
  y \\
  0  \end{array}\]

\[\begin{array}{l}
3x^2 - 12x + 13\\
3(0)^2 - 12(0) + 13 \\
13  \end{array}\]

\(\hspace{25pt}\)LS \(\lt\) RS

The point \((0,0)\) satisfies the inequality, so it and all other points on that side of the boundary are solutions. Shade the regions that includes the test point.