Today I made a change where each chapter has it's most popular solution given away for free, without even having to log in. This is a replacement for the previous free trial system which was definitely sub-optimal in that a significant number of students were getting multiple free trials by entering multiple email addresses. An enormous amount of time went into preparing for and recording so many videos, and doing that required foregoing income from my regular classroom teaching job in order to do it. I support a family of four, with two small children, so I need to insist on some positive cashflow. Nevertheless, many thanks to the students who have paid for access, since your support is invaluable, and helps make the sacrifice of not teaching in the classroom in order to make these videos worthwhile. I hope you're finding good value, and that the small cost is not onerous.