solving radical equations and factoring quadratics.
Once you've learned the basic terms and techniques, you can attempt the exercises. For the first one, a good start would be to subtract the x to the right-hand side, and then square both sides, keeping in mind that (8 - x)^2 means (8 - x)(8 - x).
For the second one, I'm not sure if they want you to square first, and then solve by factoring, or else rearrange as follows:
. . . . .
...and then solving by factoring this quadratic-type equation. Check your book and your class notes for advice on this.
If you get stuck, please reply showing all of your work and reasoning so far. Thank you!