QUADRATIC FUNCTIONS Solving Quadratic Inequalities (Page 1 of 2)

Solving a quadratic inequality is nearly the same as solving an equation. In fact, we solve the equation first using the x-intercept method, then analyze the graph to determine the solution set of the inequality.

For example, we will solve the inequality x^2-3 >= 2x+4. Get a zero on one side of the inequality first: x^2-2x-7 >= 0.

Now replace the inequality symbol with an equal sign: x^2-2x-7 = 0. This equation was solved in a previous example using CALC zero and the solutions were determined to be x ≈ -1.83 and x ≈ 3.83. The graph of the function represented by the left side of the equation is shown.

Y= key....

GRAPH key.

 Calculator screen image. Calculator screen image.
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