To test if the graph lies above or below the x axis create a number line with intervals Then choose test values before in between and after the intervals to determine if the function is positive or negative in that area A positive value means the graph is above the axis and a negative value means the graph is below the axis Try This Practice testing values to determine if the values are above or below the axis Circle if the graph of f x would be positive or negative in areas A B C and D Area D is done for you below A B C f x x 2 x 1 x 3 x axis Area A Area B Area C Area D 2 x 10 f 10 Match the appropriate test values for each area x 10 x 1 5 x 5 x 0 12 11 7 1 12 77 3 D x 2 Sign of f x x 1 x 3 positive