This preview shows page 1. Sign up to view the full content.
Unformatted text preview: on must have at least one zero in between.
Graphically, this means that a parabola can’t be above the x-axis at one point and below the x-axis
at another point without crossing the x-axis. This allows us to determine the sign of all of the
function values on a given interval by testing the function at just one value in the interval. This
gives us the following. 1 We will give this property a name in Chapter 3 and revisit this concept then. 2.4 Inequalities 161
Steps for Solving a Quadratic Inequality 1. Rewrite the inequality, if necessary, as a quadratic function f (x) on one side of the inequality
and 0 on the other.
2. Find the zeros of f and place them on the number line with the number 0 above them.
3. Choose a real number, called a test value, in each of the intervals determined in step 2.
4. Determine the sign of f (x) for each test value in step 3, and write that sign above the
5. Choose the intervals which correspond to the correct sign to solve the inequality. Exa...
View Full Document