same way as u do for a function. here u see the regions where the function is concave that where the derivative is decreasing and places where the function is convex or the derivative increases the place where derivative is max/min.. the double derivative is 0.
here u see the regions where the function is concave that where the derivative is decreasing and places where the function is convex or the derivative increases the place where derivative is max/min.. the double derivative is 0.