Inequalities that involve more than two factors, such as (3x - 4)(x + 2)(x + 6) ≤ 0, can be solved using an extension of the method shown in to see how the method is extended.

The number line from Exercise 88 should show four intervals formed by the three points. For each interval, choose a test value from the interval and decide whether it satisfies the original inequality.

Exercise 88 

Plot the three solutions in Exercise 87 on a number line, using closed circles because of the non strict inequality, ≤.