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3.3 Quadratic Inequalities we can solve: 3x + 2 > 5 (linear inequality) how about x2 - 4 > 0 ? (quadratic inequality) need to use a completely different method just look at the graph of f(x) = x2 - 4: y x Note: x2 - 4 > 0 (above the x-axis) for x < -2 or x > 2 so the solution to the inequality is: (-, -2) (2, ) You can do this without using your graphing calculator (please don’t use it!); use the graphical method, p. 207. Here’s how to solve x2 - 4 > 0 : 1. Determine if the parabola opens up or down: the leading coefficient is > 0 up the leading coefficient is < 0 down 2. Determine its x-intercepts: solve x2 - 4 = 0 3. Make a rough graph (very rough - only needs to show the parabola passing through the intercepts and whether the parabola opens up or down) – this step is required in order to support your answer! 4. Write your answer 3.3-1