Applying Descartes rule of signs with all positive terms

The video tutorial explains how to use Descartes' Rule of Signs to determine the possible number of positive and negative real zeros of a polynomial function. The instructor demonstrates the process by evaluating the polynomial for changes in sign, first for positive zeros and then for negative zeros by substituting negative values. The conclusion highlights the importance of understanding sign changes to predict the number of real zeros accurately.

What is the significance of the number of sign changes in determining real zeros?

What conclusions can be drawn about the positive and negative real zeros based on the analysis?