Here's the link to the review video for solving a quadratic equation :  
https://www.youtube.com/watch?v=FB7Vq3rlB44

Here's the link to the review video for solving a quadratic equation with the quadratic formula :
https://www.youtube.com/watch?v=du07bddMZ2k

Here's the link to the review video for solving a system of equations by elimination :  
https://www.youtube.com/watch?v=38FfSiooC7o

Here's the link to the review video for solving a system of equations by substitution :  
https://www.youtube.com/watch?v=wKVhfuQnNKI

Here's the link to the review video for simplifying radicals :
https://www.youtube.com/watch?v=a7pvoc71Am0

Here's the link to the review video for simplfying radical expressions :  
https://www.youtube.com/watch?v=yE2r9QVCm2Y

Here's the link to the review video for pythagorean theorem :  
https://www.youtube.com/watch?v=7DoyH54oTDE