If you need additional help with square roots, check out my website by doing a "Bing" search for my last name "Rapalje". Look for "Rapalje Homepage" at the top of the search list, and choose the link on my homepage "Basic, Intermediate and College Algebra: One Step at a Time." Click on "Basic Algebra", and you will find a couple of sections near the end of Chapter 5 on "Radicals". My non-traditional explanation should be easier to understand than your textbook!
See also my "MATH IN LIVING COLOR", "Intermediate Algebra", "Chapter 3".
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Dr. Robert J. Rapalje, Retired
Seminole Community College
Altamonte Springs Campus
Florida