Well whenever any function crosses the x-axis, it means that the y-value is equal to zero.
In this case when the derivative passes the x-axis it indicates the tangent line corresponding to that x-value has a slope of zero, which when plotted is a horizontal line.
This means that the graph f has 3 horizontal tangent lines.
That is 12 over 5 and u will divide the numerator by the denominator to get 2.4 Dont know if thts exactly right bcuz its been a while since i learned this but i hope it helps
