Answer with explanation:
→Sign charts are mainly used for solving Inequality.
→Sign charts are also used to determine in which interval function is increasing and in which interval it is decreasing.That is concept of Increasing and Decreasing Phenomenon is used in functions.
→In sign chart,we substitute real numbers after and before Zero of the inequality in the function to check which side on the number line or inside which interval the inequality is satisfied.
→So, to fill out a sign chart, you will need to use test numbers before and after each of the function's zeros and in the given Function (Polynomial).
Whether these numbers satisfy the Inequality or not to find the interval.