Subtracting two radical expressions with variable radicands

The video tutorial covers simplifying radicals by rewriting them as square numbers and subtracting them when they have the same radican and root. The teacher explains the process step-by-step, emphasizing the importance of using square numbers like four and nine to simplify the radicals. The tutorial also highlights the need to subtract coefficients when the radican and root are identical.

What does the teacher emphasize about the coefficients when subtracting radicals?

What is the result of subtracting 3 sqrt(7X) from 8 sqrt(7X)?